set @save_optimizer_switch_jcl6=@@optimizer_switch; set @@optimizer_switch='optimize_join_buffer_size=on'; set @@optimizer_switch='semijoin_with_cache=on'; set @@optimizer_switch='outer_join_with_cache=on'; set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on'; set join_cache_level=6; show variables like 'join_cache_level'; Variable_name Value join_cache_level 6 set @optimizer_switch_for_join_outer_test=@@optimizer_switch; set @join_cache_level_for_join_outer_test=@@join_cache_level; drop table if exists t0,t1,t2,t3,t4,t5; SET @save_optimizer_switch=@@optimizer_switch; SET optimizer_switch=ifnull(@optimizer_switch_for_join_outer_test,'outer_join_with_cache=off'); set join_cache_level=@join_cache_level_for_join_outer_test; CREATE TABLE t1 ( grp int(11) default NULL, a bigint(20) unsigned default NULL, c char(10) NOT NULL default '' ) ENGINE=MyISAM; INSERT INTO t1 VALUES (1,1,'a'),(2,2,'b'),(2,3,'c'),(3,4,'E'),(3,5,'C'),(3,6,'D'),(NULL,NULL,''); create table t2 (id int, a bigint unsigned not null, c char(10), d int, primary key (a)); insert into t2 values (1,1,"a",1),(3,4,"A",4),(3,5,"B",5),(3,6,"C",6),(4,7,"D",7); select t1.*,t2.* from t1 JOIN t2 where t1.a=t2.a; grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) order by t1.grp,t1.a,t2.c; grp a c id a c d NULL NULL NULL NULL NULL NULL 1 1 a 1 1 a 1 2 2 b NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from { oj t2 left outer join t1 on (t1.a=t2.a) }; grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 NULL NULL NULL 4 7 D 7 select t1.*,t2.* from t1 as t0,{ oj t2 left outer join t1 on (t1.a=t2.a) } WHERE t0.a=2; grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 NULL NULL NULL 4 7 D 7 select t1.*,t2.* from t1 left join t2 using (a); grp a c id a c d 1 1 a 1 1 a 1 2 2 b NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 NULL NULL NULL NULL NULL NULL select t1.*,t2.* from t1 left join t2 using (a) where t1.a=t2.a; grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from t1 left join t2 using (a,c); grp a c id a c d 1 1 a 1 1 a 1 2 2 b NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL 3 4 E NULL NULL NULL NULL 3 5 C NULL NULL NULL NULL 3 6 D NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL select t1.*,t2.* from t1 left join t2 using (c); grp a c id a c d 1 1 a 1 1 a 1 1 1 a 3 4 A 4 2 2 b 3 5 B 5 2 3 c 3 6 C 6 3 4 E NULL NULL NULL NULL 3 5 C 3 6 C 6 3 6 D 4 7 D 7 NULL NULL NULL NULL NULL NULL select t1.*,t2.* from t1 natural left outer join t2; grp a c id a c d 1 1 a 1 1 a 1 2 2 b NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL 3 4 E NULL NULL NULL NULL 3 5 C NULL NULL NULL NULL 3 6 D NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) where t2.id=3; grp a c id a c d 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from t1 left join t2 on (t1.a=t2.a) where t2.id is null; grp a c id a c d 2 2 b NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL explain select t1.*,t2.* from t1,t2 where t1.a=t2.a and isnull(t2.a)=1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE explain select t1.*,t2.* from t1 left join t2 on t1.a=t2.a where isnull(t2.a)=1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 7 1 SIMPLE t2 eq_ref PRIMARY PRIMARY 8 test.t1.a 1 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan select t1.*,t2.*,t3.a from t1 left join t2 on (t1.a=t2.a) left join t1 as t3 on (t2.a=t3.a); grp a c id a c d a 1 1 a 1 1 a 1 1 2 2 b NULL NULL NULL NULL NULL 2 3 c NULL NULL NULL NULL NULL 3 4 E 3 4 A 4 4 3 5 C 3 5 B 5 5 3 6 D 3 6 C 6 6 NULL NULL NULL NULL NULL NULL NULL explain select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t1.a=t3.a); ERROR 42S22: Unknown column 't3.a' in 'on clause' select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t1.a=t3.a); ERROR 42S22: Unknown column 't3.a' in 'on clause' select t1.*,t2.*,t3.a from t1 left join t2 on (t3.a=t2.a) left join t1 as t3 on (t2.a=t3.a); ERROR 42S22: Unknown column 't3.a' in 'on clause' select t1.*,t2.* from t1 inner join t2 using (a); grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from t1 inner join t2 on (t1.a=t2.a); grp a c id a c d 1 1 a 1 1 a 1 3 4 E 3 4 A 4 3 5 C 3 5 B 5 3 6 D 3 6 C 6 select t1.*,t2.* from t1 natural join t2; grp a c id a c d 1 1 a 1 1 a 1 drop table t1,t2; CREATE TABLE t1 ( usr_id INT unsigned NOT NULL, uniq_id INT unsigned NOT NULL AUTO_INCREMENT, start_num INT unsigned NOT NULL DEFAULT 1, increment INT unsigned NOT NULL DEFAULT 1, PRIMARY KEY (uniq_id), INDEX usr_uniq_idx (usr_id, uniq_id), INDEX uniq_usr_idx (uniq_id, usr_id) ); CREATE TABLE t2 ( id INT unsigned NOT NULL DEFAULT 0, usr2_id INT unsigned NOT NULL DEFAULT 0, max INT unsigned NOT NULL DEFAULT 0, c_amount INT unsigned NOT NULL DEFAULT 0, d_max INT unsigned NOT NULL DEFAULT 0, d_num INT unsigned NOT NULL DEFAULT 0, orig_time INT unsigned NOT NULL DEFAULT 0, c_time INT unsigned NOT NULL DEFAULT 0, active ENUM ("no","yes") NOT NULL, PRIMARY KEY (id,usr2_id), INDEX id_idx (id), INDEX usr2_idx (usr2_id) ); INSERT INTO t1 VALUES (3,NULL,0,50),(3,NULL,0,200),(3,NULL,0,25),(3,NULL,0,84676),(3,NULL,0,235),(3,NULL,0,10),(3,NULL,0,3098),(3,NULL,0,2947),(3,NULL,0,8987),(3,NULL,0,8347654),(3,NULL,0,20398),(3,NULL,0,8976),(3,NULL,0,500),(3,NULL,0,198); SELECT t1.usr_id,t1.uniq_id,t1.increment, t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 ORDER BY t2.c_amount; usr_id uniq_id increment usr2_id c_amount max 3 4 84676 NULL NULL NULL SELECT t1.usr_id,t1.uniq_id,t1.increment, t2.usr2_id,t2.c_amount,t2.max FROM t2 RIGHT JOIN t1 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 ORDER BY t2.c_amount; usr_id uniq_id increment usr2_id c_amount max 3 4 84676 NULL NULL NULL INSERT INTO t2 VALUES (2,3,3000,6000,0,0,746584,837484,'yes'); INSERT INTO t2 VALUES (2,3,3000,6000,0,0,746584,837484,'yes'); ERROR 23000: Duplicate entry '2-3' for key 'PRIMARY' INSERT INTO t2 VALUES (7,3,1000,2000,0,0,746294,937484,'yes'); SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 ORDER BY t2.c_amount; usr_id uniq_id increment usr2_id c_amount max 3 4 84676 NULL NULL NULL SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4 GROUP BY t2.c_amount; usr_id uniq_id increment usr2_id c_amount max 3 4 84676 NULL NULL NULL SELECT t1.usr_id,t1.uniq_id,t1.increment,t2.usr2_id,t2.c_amount,t2.max FROM t1 LEFT JOIN t2 ON t2.id = t1.uniq_id WHERE t1.uniq_id = 4; usr_id uniq_id increment usr2_id c_amount max 3 4 84676 NULL NULL NULL drop table t1,t2; CREATE TABLE t1 ( cod_asig int(11) DEFAULT '0' NOT NULL, desc_larga_cat varchar(80) DEFAULT '' NOT NULL, desc_larga_cas varchar(80) DEFAULT '' NOT NULL, desc_corta_cat varchar(40) DEFAULT '' NOT NULL, desc_corta_cas varchar(40) DEFAULT '' NOT NULL, cred_total double(3,1) DEFAULT '0.0' NOT NULL, pre_requisit int(11), co_requisit int(11), preco_requisit int(11), PRIMARY KEY (cod_asig) ); INSERT INTO t1 VALUES (10360,'asdfggfg','Introduccion a los Ordenadores I','asdfggfg','Introduccio Ordinadors I',6.0,NULL,NULL,NULL); INSERT INTO t1 VALUES (10361,'Components i Circuits Electronics I','Componentes y Circuitos Electronicos I','Components i Circuits Electronics I','Comp. i Circ. Electr. I',6.0,NULL,NULL,NULL); INSERT INTO t1 VALUES (10362,'Laboratori d`Ordinadors','Laboratorio de Ordenadores','Laboratori d`Ordinadors','Laboratori Ordinadors',4.5,NULL,NULL,NULL); INSERT INTO t1 VALUES (10363,'Tecniques de Comunicacio Oral i Escrita','Tecnicas de Comunicacion Oral y Escrita','Tecniques de Comunicacio Oral i Escrita','Tec. Com. Oral i Escrita',4.5,NULL,NULL,NULL); INSERT INTO t1 VALUES (11403,'Projecte Fi de Carrera','Proyecto Fin de Carrera','Projecte Fi de Carrera','PFC',9.0,NULL,NULL,NULL); INSERT INTO t1 VALUES (11404,'+lgebra lineal','Algebra lineal','+lgebra lineal','+lgebra lineal',15.0,NULL,NULL,NULL); INSERT INTO t1 VALUES (11405,'+lgebra lineal','Algebra lineal','+lgebra lineal','+lgebra lineal',18.0,NULL,NULL,NULL); INSERT INTO t1 VALUES (11406,'Calcul Infinitesimal','Cßlculo Infinitesimal','Calcul Infinitesimal','Calcul Infinitesimal',15.0,NULL,NULL,NULL); CREATE TABLE t2 ( idAssignatura int(11) DEFAULT '0' NOT NULL, Grup int(11) DEFAULT '0' NOT NULL, Places smallint(6) DEFAULT '0' NOT NULL, PlacesOcupades int(11) DEFAULT '0', PRIMARY KEY (idAssignatura,Grup) ); INSERT INTO t2 VALUES (10360,12,333,0); INSERT INTO t2 VALUES (10361,30,2,0); INSERT INTO t2 VALUES (10361,40,3,0); INSERT INTO t2 VALUES (10360,45,10,0); INSERT INTO t2 VALUES (10362,10,12,0); INSERT INTO t2 VALUES (10360,55,2,0); INSERT INTO t2 VALUES (10360,70,0,0); INSERT INTO t2 VALUES (10360,565656,0,0); INSERT INTO t2 VALUES (10360,32767,7,0); INSERT INTO t2 VALUES (10360,33,8,0); INSERT INTO t2 VALUES (10360,7887,85,0); INSERT INTO t2 VALUES (11405,88,8,0); INSERT INTO t2 VALUES (10360,0,55,0); INSERT INTO t2 VALUES (10360,99,0,0); INSERT INTO t2 VALUES (11411,30,10,0); INSERT INTO t2 VALUES (11404,0,0,0); INSERT INTO t2 VALUES (10362,11,111,0); INSERT INTO t2 VALUES (10363,33,333,0); INSERT INTO t2 VALUES (11412,55,0,0); INSERT INTO t2 VALUES (50003,66,6,0); INSERT INTO t2 VALUES (11403,5,0,0); INSERT INTO t2 VALUES (11406,11,11,0); INSERT INTO t2 VALUES (11410,11410,131,0); INSERT INTO t2 VALUES (11416,11416,32767,0); INSERT INTO t2 VALUES (11409,0,0,0); CREATE TABLE t3 ( id int(11) NOT NULL auto_increment, dni_pasaporte char(16) DEFAULT '' NOT NULL, idPla int(11) DEFAULT '0' NOT NULL, cod_asig int(11) DEFAULT '0' NOT NULL, any smallint(6) DEFAULT '0' NOT NULL, quatrimestre smallint(6) DEFAULT '0' NOT NULL, estat char(1) DEFAULT 'M' NOT NULL, PRIMARY KEY (id), UNIQUE dni_pasaporte (dni_pasaporte,idPla), UNIQUE dni_pasaporte_2 (dni_pasaporte,idPla,cod_asig,any,quatrimestre) ); INSERT INTO t3 VALUES (1,'11111111',1,10362,98,1,'M'); CREATE TABLE t4 ( id int(11) NOT NULL auto_increment, papa int(11) DEFAULT '0' NOT NULL, fill int(11) DEFAULT '0' NOT NULL, idPla int(11) DEFAULT '0' NOT NULL, PRIMARY KEY (id), KEY papa (idPla,papa), UNIQUE papa_2 (idPla,papa,fill) ); INSERT INTO t4 VALUES (1,-1,10360,1); INSERT INTO t4 VALUES (2,-1,10361,1); INSERT INTO t4 VALUES (3,-1,10362,1); SELECT DISTINCT fill,desc_larga_cat,cred_total,Grup,Places,PlacesOcupades FROM t4 LEFT JOIN t3 ON t3.cod_asig=fill AND estat='S' AND dni_pasaporte='11111111' AND t3.idPla=1 , t2,t1 WHERE fill=t1.cod_asig AND Places>PlacesOcupades AND fill=idAssignatura AND t4.idPla=1 AND papa=-1; fill desc_larga_cat cred_total Grup Places PlacesOcupades 10360 asdfggfg 6.0 0 55 0 10360 asdfggfg 6.0 12 333 0 10360 asdfggfg 6.0 32767 7 0 10360 asdfggfg 6.0 33 8 0 10360 asdfggfg 6.0 45 10 0 10360 asdfggfg 6.0 55 2 0 10360 asdfggfg 6.0 7887 85 0 10361 Components i Circuits Electronics I 6.0 30 2 0 10361 Components i Circuits Electronics I 6.0 40 3 0 10362 Laboratori d`Ordinadors 4.5 10 12 0 10362 Laboratori d`Ordinadors 4.5 11 111 0 SELECT DISTINCT fill,t3.idPla FROM t4 LEFT JOIN t3 ON t3.cod_asig=t4.fill AND t3.estat='S' AND t3.dni_pasaporte='1234' AND t3.idPla=1 ; fill idPla 10360 NULL 10361 NULL 10362 NULL INSERT INTO t3 VALUES (3,'1234',1,10360,98,1,'S'); SELECT DISTINCT fill,t3.idPla FROM t4 LEFT JOIN t3 ON t3.cod_asig=t4.fill AND t3.estat='S' AND t3.dni_pasaporte='1234' AND t3.idPla=1 ; fill idPla 10360 1 10361 NULL 10362 NULL drop table t1,t2,t3,test.t4; CREATE TABLE t1 ( id smallint(5) unsigned NOT NULL auto_increment, name char(60) DEFAULT '' NOT NULL, PRIMARY KEY (id) ); INSERT INTO t1 VALUES (1,'Antonio Paz'); INSERT INTO t1 VALUES (2,'Lilliana Angelovska'); INSERT INTO t1 VALUES (3,'Thimble Smith'); CREATE TABLE t2 ( id smallint(5) unsigned NOT NULL auto_increment, owner smallint(5) unsigned DEFAULT '0' NOT NULL, name char(60), PRIMARY KEY (id) ); INSERT INTO t2 VALUES (1,1,'El Gato'); INSERT INTO t2 VALUES (2,1,'Perrito'); INSERT INTO t2 VALUES (3,3,'Happy'); select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner); name name id Antonio Paz El Gato 1 Antonio Paz Perrito 2 Lilliana Angelovska NULL NULL Thimble Smith Happy 3 select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.id is null; name name id Lilliana Angelovska NULL NULL explain select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.id is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t2 hash_ALL NULL #hash#$hj 2 test.t1.id 3 Using where; Not exists; Using join buffer (flat, BNLH join) explain select t1.name, t2.name, t2.id from t1 left join t2 on (t1.id = t2.owner) where t2.name is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t2 hash_ALL NULL #hash#$hj 2 test.t1.id 3 Using where; Using join buffer (flat, BNLH join) select count(*) from t1 left join t2 on (t1.id = t2.owner); count(*) 4 select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner); name name id Antonio Paz El Gato 1 Antonio Paz Perrito 2 Lilliana Angelovska NULL NULL Thimble Smith Happy 3 select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.id is null; name name id Lilliana Angelovska NULL NULL explain select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.id is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t2 hash_ALL NULL #hash#$hj 2 test.t1.id 3 Using where; Not exists; Using join buffer (flat, BNLH join) explain select t1.name, t2.name, t2.id from t2 right join t1 on (t1.id = t2.owner) where t2.name is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t2 hash_ALL NULL #hash#$hj 2 test.t1.id 3 Using where; Using join buffer (flat, BNLH join) select count(*) from t2 right join t1 on (t1.id = t2.owner); count(*) 4 select t1.name, t2.name, t2.id,t3.id from t2 right join t1 on (t1.id = t2.owner) left join t1 as t3 on t3.id=t2.owner; name name id id Antonio Paz El Gato 1 1 Antonio Paz Perrito 2 1 Lilliana Angelovska NULL NULL NULL Thimble Smith Happy 3 3 select t1.name, t2.name, t2.id,t3.id from t1 right join t2 on (t1.id = t2.owner) right join t1 as t3 on t3.id=t2.owner; name name id id Antonio Paz El Gato 1 1 Antonio Paz Perrito 2 1 NULL NULL NULL 2 Thimble Smith Happy 3 3 select t1.name, t2.name, t2.id, t2.owner, t3.id from t1 left join t2 on (t1.id = t2.owner) right join t1 as t3 on t3.id=t2.owner; name name id owner id Antonio Paz El Gato 1 1 1 Antonio Paz Perrito 2 1 1 NULL NULL NULL NULL 2 Thimble Smith Happy 3 3 3 drop table t1,t2; create table t1 (id int not null, str char(10), index(str)); insert into t1 values (1, null), (2, null), (3, "foo"), (4, "bar"); select * from t1 where str is not null order by id; id str 3 foo 4 bar select * from t1 where str is null; id str 1 NULL 2 NULL drop table t1; CREATE TABLE t1 ( t1_id bigint(21) NOT NULL auto_increment, PRIMARY KEY (t1_id) ); CREATE TABLE t2 ( t2_id bigint(21) NOT NULL auto_increment, PRIMARY KEY (t2_id) ); CREATE TABLE t3 ( t3_id bigint(21) NOT NULL auto_increment, PRIMARY KEY (t3_id) ); CREATE TABLE t4 ( seq_0_id bigint(21) DEFAULT '0' NOT NULL, seq_1_id bigint(21) DEFAULT '0' NOT NULL, KEY seq_0_id (seq_0_id), KEY seq_1_id (seq_1_id) ); CREATE TABLE t5 ( seq_0_id bigint(21) DEFAULT '0' NOT NULL, seq_1_id bigint(21) DEFAULT '0' NOT NULL, KEY seq_1_id (seq_1_id), KEY seq_0_id (seq_0_id) ); insert into t1 values (1); insert into t2 values (1); insert into t3 values (1); insert into t4 values (1,1); insert into t5 values (1,1); explain select * from t3 left join t4 on t4.seq_1_id = t2.t2_id left join t1 on t1.t1_id = t4.seq_0_id left join t5 on t5.seq_0_id = t1.t1_id left join t2 on t2.t2_id = t5.seq_1_id where t3.t3_id = 23; ERROR 42S22: Unknown column 't2.t2_id' in 'on clause' drop table t1,t2,t3,t4,t5; create table t1 (n int, m int, o int, key(n)); create table t2 (n int not null, m int, o int, primary key(n)); insert into t1 values (1, 2, 11), (1, 2, 7), (2, 2, 8), (1,2,9),(1,3,9); insert into t2 values (1, 2, 3),(2, 2, 8), (4,3,9),(3,2,10); select t1.*, t2.* from t1 left join t2 on t1.n = t2.n and t1.m = t2.m where t1.n = 1; n m o n m o 1 2 11 1 2 3 1 2 7 1 2 3 1 2 9 1 2 3 1 3 9 NULL NULL NULL select t1.*, t2.* from t1 left join t2 on t1.n = t2.n and t1.m = t2.m where t1.n = 1 order by t1.o; n m o n m o 1 2 11 1 2 3 1 2 7 1 2 3 1 2 9 1 2 3 1 3 9 NULL NULL NULL drop table t1,t2; CREATE TABLE t1 (id1 INT NOT NULL PRIMARY KEY, dat1 CHAR(1), id2 INT); INSERT INTO t1 VALUES (1,'a',1); INSERT INTO t1 VALUES (2,'b',1); INSERT INTO t1 VALUES (3,'c',2); CREATE TABLE t2 (id2 INT NOT NULL PRIMARY KEY, dat2 CHAR(1)); INSERT INTO t2 VALUES (1,'x'); INSERT INTO t2 VALUES (2,'y'); INSERT INTO t2 VALUES (3,'z'); SELECT t2.id2 FROM t2 LEFT OUTER JOIN t1 ON t1.id2 = t2.id2 WHERE id1 IS NULL; id2 3 SELECT t2.id2 FROM t2 NATURAL LEFT OUTER JOIN t1 WHERE id1 IS NULL; id2 3 drop table t1,t2; create table t1 ( color varchar(20), name varchar(20) ); insert into t1 values ( 'red', 'apple' ); insert into t1 values ( 'yellow', 'banana' ); insert into t1 values ( 'green', 'lime' ); insert into t1 values ( 'black', 'grape' ); insert into t1 values ( 'blue', 'blueberry' ); create table t2 ( count int, color varchar(20) ); insert into t2 values (10, 'green'); insert into t2 values (5, 'black'); insert into t2 values (15, 'white'); insert into t2 values (7, 'green'); select * from t1; color name red apple yellow banana green lime black grape blue blueberry select * from t2; count color 10 green 5 black 15 white 7 green select * from t2 natural join t1; color count name green 10 lime green 7 lime black 5 grape select t2.count, t1.name from t2 natural join t1; count name 10 lime 7 lime 5 grape select t2.count, t1.name from t2 inner join t1 using (color); count name 10 lime 7 lime 5 grape drop table t1; drop table t2; CREATE TABLE t1 ( pcode varchar(8) DEFAULT '' NOT NULL ); INSERT INTO t1 VALUES ('kvw2000'),('kvw2001'),('kvw3000'),('kvw3001'),('kvw3002'),('kvw3500'),('kvw3501'),('kvw3502'),('kvw3800'),('kvw3801'),('kvw3802'),('kvw3900'),('kvw3901'),('kvw3902'),('kvw4000'),('kvw4001'),('kvw4002'),('kvw4200'),('kvw4500'),('kvw5000'),('kvw5001'),('kvw5500'),('kvw5510'),('kvw5600'),('kvw5601'),('kvw6000'),('klw1000'),('klw1020'),('klw1500'),('klw2000'),('klw2001'),('klw2002'),('kld2000'),('klw2500'),('kmw1000'),('kmw1500'),('kmw2000'),('kmw2001'),('kmw2100'),('kmw3000'),('kmw3200'); CREATE TABLE t2 ( pcode varchar(8) DEFAULT '' NOT NULL, KEY pcode (pcode) ); INSERT INTO t2 VALUES ('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw2000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3000'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw3500'),('kvw6000'),('kvw6000'),('kld2000'); SELECT t1.pcode, IF(ISNULL(t2.pcode), 0, COUNT(*)) AS count FROM t1 LEFT JOIN t2 ON t1.pcode = t2.pcode GROUP BY t1.pcode; pcode count kld2000 1 klw1000 0 klw1020 0 klw1500 0 klw2000 0 klw2001 0 klw2002 0 klw2500 0 kmw1000 0 kmw1500 0 kmw2000 0 kmw2001 0 kmw2100 0 kmw3000 0 kmw3200 0 kvw2000 26 kvw2001 0 kvw3000 36 kvw3001 0 kvw3002 0 kvw3500 26 kvw3501 0 kvw3502 0 kvw3800 0 kvw3801 0 kvw3802 0 kvw3900 0 kvw3901 0 kvw3902 0 kvw4000 0 kvw4001 0 kvw4002 0 kvw4200 0 kvw4500 0 kvw5000 0 kvw5001 0 kvw5500 0 kvw5510 0 kvw5600 0 kvw5601 0 kvw6000 2 SELECT SQL_BIG_RESULT t1.pcode, IF(ISNULL(t2.pcode), 0, COUNT(*)) AS count FROM t1 LEFT JOIN t2 ON t1.pcode = t2.pcode GROUP BY t1.pcode; pcode count kld2000 1 klw1000 0 klw1020 0 klw1500 0 klw2000 0 klw2001 0 klw2002 0 klw2500 0 kmw1000 0 kmw1500 0 kmw2000 0 kmw2001 0 kmw2100 0 kmw3000 0 kmw3200 0 kvw2000 26 kvw2001 0 kvw3000 36 kvw3001 0 kvw3002 0 kvw3500 26 kvw3501 0 kvw3502 0 kvw3800 0 kvw3801 0 kvw3802 0 kvw3900 0 kvw3901 0 kvw3902 0 kvw4000 0 kvw4001 0 kvw4002 0 kvw4200 0 kvw4500 0 kvw5000 0 kvw5001 0 kvw5500 0 kvw5510 0 kvw5600 0 kvw5601 0 kvw6000 2 drop table t1,t2; CREATE TABLE t1 ( id int(11), pid int(11), rep_del tinyint(4), KEY id (id), KEY pid (pid) ); INSERT INTO t1 VALUES (1,NULL,NULL); INSERT INTO t1 VALUES (2,1,NULL); select * from t1 LEFT JOIN t1 t2 ON (t1.id=t2.pid) AND t2.rep_del IS NULL; id pid rep_del id pid rep_del 1 NULL NULL 2 1 NULL 2 1 NULL NULL NULL NULL create index rep_del ON t1(rep_del); select * from t1 LEFT JOIN t1 t2 ON (t1.id=t2.pid) AND t2.rep_del IS NULL; id pid rep_del id pid rep_del 1 NULL NULL 2 1 NULL 2 1 NULL NULL NULL NULL drop table t1; CREATE TABLE t1 ( id int(11) DEFAULT '0' NOT NULL, name tinytext DEFAULT '' NOT NULL, UNIQUE id (id) ); INSERT INTO t1 VALUES (1,'yes'),(2,'no'); CREATE TABLE t2 ( id int(11) DEFAULT '0' NOT NULL, idx int(11) DEFAULT '0' NOT NULL, UNIQUE id (id,idx) ); INSERT INTO t2 VALUES (1,1); explain SELECT * from t1 left join t2 on t1.id=t2.id where t2.id IS NULL; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 1 SIMPLE t2 ref id id 4 test.t1.id 1 Using where; Using index; Not exists SELECT * from t1 left join t2 on t1.id=t2.id where t2.id IS NULL; id name id idx 2 no NULL NULL drop table t1,t2; create table t1 (bug_id mediumint, reporter mediumint); create table t2 (bug_id mediumint, who mediumint, index(who)); insert into t2 values (1,1),(1,2); insert into t1 values (1,1),(2,1); SELECT * FROM t1 LEFT JOIN t2 ON (t1.bug_id = t2.bug_id AND t2.who = 2) WHERE (t1.reporter = 2 OR t2.who = 2); bug_id reporter bug_id who 1 1 1 2 drop table t1,t2; create table t1 (fooID smallint unsigned auto_increment, primary key (fooID)); create table t2 (fooID smallint unsigned not null, barID smallint unsigned not null, primary key (fooID,barID)); insert into t1 (fooID) values (10),(20),(30); insert into t2 values (10,1),(20,2),(30,3); explain select * from t2 left join t1 on t1.fooID = t2.fooID and t1.fooID = 30; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 index NULL PRIMARY 4 NULL 3 Using index 1 SIMPLE t1 const PRIMARY PRIMARY 2 const 1 Using where; Using index select * from t2 left join t1 on t1.fooID = t2.fooID and t1.fooID = 30; fooID barID fooID 10 1 NULL 20 2 NULL 30 3 30 select * from t2 left join t1 ignore index(primary) on t1.fooID = t2.fooID and t1.fooID = 30; fooID barID fooID 10 1 NULL 20 2 NULL 30 3 30 drop table t1,t2; create table t1 (i int); create table t2 (i int); create table t3 (i int); insert into t1 values(1),(2); insert into t2 values(2),(3); insert into t3 values(2),(4); select * from t1 natural left join t2 natural left join t3; i 1 2 select * from t1 natural left join t2 where (t2.i is not null)=0; i 1 select * from t1 natural left join t2 where (t2.i is not null) is not null; i 1 2 select * from t1 natural left join t2 where (i is not null)=0; i select * from t1 natural left join t2 where (i is not null) is not null; i 1 2 drop table t1,t2,t3; create table t1 (f1 integer,f2 integer,f3 integer); create table t2 (f2 integer,f4 integer); create table t3 (f3 integer,f5 integer); select * from t1 left outer join t2 using (f2) left outer join t3 using (f3); f3 f2 f1 f4 f5 drop table t1,t2,t3; create table t1 (a1 int, a2 int); create table t2 (b1 int not null, b2 int); create table t3 (c1 int, c2 int); insert into t1 values (1,2), (2,2), (3,2); insert into t2 values (1,3), (2,3); insert into t3 values (2,4), (3,4); select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null; a1 a2 b1 b2 c1 c2 3 2 NULL NULL 3 4 1 2 1 3 NULL NULL 2 2 2 3 NULL NULL explain select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t2 hash_ALL NULL #hash#$hj 4 test.t1.a1 2 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t3 hash_ALL NULL #hash#$hj 5 test.t1.a1 2 Using where; Using join buffer (incremental, BNLH join) drop table t1, t2, t3; create table t1 ( a int(11), b char(10), key (a) ); insert into t1 (a) values (1),(2),(3),(4); create table t2 (a int); select * from t1 left join t2 on t1.a=t2.a where not (t2.a <=> t1.a); a b a 1 NULL NULL 2 NULL NULL 3 NULL NULL 4 NULL NULL select * from t1 left join t2 on t1.a=t2.a having not (t2.a <=> t1.a); a b a 1 NULL NULL 2 NULL NULL 3 NULL NULL 4 NULL NULL drop table t1,t2; create table t1 ( match_id tinyint(3) unsigned not null auto_increment, home tinyint(3) unsigned default '0', unique key match_id (match_id), key match_id_2 (match_id) ); insert into t1 values("1", "2"); create table t2 ( player_id tinyint(3) unsigned default '0', match_1_h tinyint(3) unsigned default '0', key player_id (player_id) ); insert into t2 values("1", "5"); insert into t2 values("2", "9"); insert into t2 values("3", "3"); insert into t2 values("4", "7"); insert into t2 values("5", "6"); insert into t2 values("6", "8"); insert into t2 values("7", "4"); insert into t2 values("8", "12"); insert into t2 values("9", "11"); insert into t2 values("10", "10"); explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from (t2 s left join t1 m on m.match_id = 1) order by m.match_id desc; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort 1 SIMPLE m const match_id,match_id_2 match_id 1 const 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from (t2 s left join t1 m on m.match_id = 1) order by UUX desc; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort 1 SIMPLE m const match_id,match_id_2 match_id 1 const 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan select s.*, '*', m.*, (s.match_1_h - m.home) UUX from (t2 s left join t1 m on m.match_id = 1) order by UUX desc; player_id match_1_h * match_id home UUX 8 12 * 1 2 10 9 11 * 1 2 9 10 10 * 1 2 8 2 9 * 1 2 7 6 8 * 1 2 6 4 7 * 1 2 5 5 6 * 1 2 4 1 5 * 1 2 3 7 4 * 1 2 2 3 3 * 1 2 1 explain select s.*, '*', m.*, (s.match_1_h - m.home) UUX from t2 s straight_join t1 m where m.match_id = 1 order by UUX desc; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE s ALL NULL NULL NULL NULL 10 Using temporary; Using filesort 1 SIMPLE m const match_id,match_id_2 match_id 1 const 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan select s.*, '*', m.*, (s.match_1_h - m.home) UUX from t2 s straight_join t1 m where m.match_id = 1 order by UUX desc; player_id match_1_h * match_id home UUX 8 12 * 1 2 10 9 11 * 1 2 9 10 10 * 1 2 8 2 9 * 1 2 7 6 8 * 1 2 6 4 7 * 1 2 5 5 6 * 1 2 4 1 5 * 1 2 3 7 4 * 1 2 2 3 3 * 1 2 1 drop table t1, t2; create table t1 (a int, b int, unique index idx (a, b)); create table t2 (a int, b int, c int, unique index idx (a, b)); insert into t1 values (1, 10), (1,11), (2,10), (2,11); insert into t2 values (1,10,3); select t1.a, t1.b, t2.c from t1 left join t2 on t1.a=t2.a and t1.b=t2.b and t2.c=3 where t1.a=1 and t2.c is null; a b c 1 11 NULL drop table t1, t2; CREATE TABLE t1 ( ts_id bigint(20) default NULL, inst_id tinyint(4) default NULL, flag_name varchar(64) default NULL, flag_value text, UNIQUE KEY ts_id (ts_id,inst_id,flag_name) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE t2 ( ts_id bigint(20) default NULL, inst_id tinyint(4) default NULL, flag_name varchar(64) default NULL, flag_value text, UNIQUE KEY ts_id (ts_id,inst_id,flag_name) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; INSERT INTO t1 VALUES (111056548820001, 0, 'flag1', NULL), (111056548820001, 0, 'flag2', NULL), (2, 0, 'other_flag', NULL); INSERT INTO t2 VALUES (111056548820001, 3, 'flag1', 'sss'); SELECT t1.flag_name,t2.flag_value FROM t1 LEFT JOIN t2 ON (t1.ts_id = t2.ts_id AND t1.flag_name = t2.flag_name AND t2.inst_id = 3) WHERE t1.inst_id = 0 AND t1.ts_id=111056548820001 AND t2.flag_value IS NULL; flag_name flag_value flag2 NULL DROP TABLE t1,t2; CREATE TABLE t1 ( id int(11) unsigned NOT NULL auto_increment, text_id int(10) unsigned default NULL, PRIMARY KEY (id) ); INSERT INTO t1 VALUES("1", "0"); INSERT INTO t1 VALUES("2", "10"); CREATE TABLE t2 ( text_id char(3) NOT NULL default '', language_id char(3) NOT NULL default '', text_data text, PRIMARY KEY (text_id,language_id) ); INSERT INTO t2 VALUES("0", "EN", "0-EN"); INSERT INTO t2 VALUES("0", "SV", "0-SV"); INSERT INTO t2 VALUES("10", "EN", "10-EN"); INSERT INTO t2 VALUES("10", "SV", "10-SV"); SELECT t1.id, t1.text_id, t2.text_data FROM t1 LEFT JOIN t2 ON t1.text_id = t2.text_id AND t2.language_id = 'SV' WHERE (t1.id LIKE '%' OR t2.text_data LIKE '%'); id text_id text_data 1 0 0-SV 2 10 10-SV DROP TABLE t1, t2; CREATE TABLE t0 (a0 int PRIMARY KEY); CREATE TABLE t1 (a1 int PRIMARY KEY); CREATE TABLE t2 (a2 int); CREATE TABLE t3 (a3 int); INSERT INTO t0 VALUES (1); INSERT INTO t1 VALUES (1); INSERT INTO t2 VALUES (1), (2); INSERT INTO t3 VALUES (1), (2); SELECT * FROM t1 LEFT JOIN t2 ON a1=0; a1 a2 1 NULL EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON a1=0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 Using where SELECT * FROM t1 LEFT JOIN (t2,t3) ON a1=0; a1 a2 a3 1 NULL NULL EXPLAIN SELECT * FROM t1 LEFT JOIN (t2,t3) ON a1=0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=0 WHERE a0=a1; a0 a1 a2 a3 1 1 NULL NULL EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=0 WHERE a0=a1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t0 system PRIMARY NULL NULL NULL 1 1 SIMPLE t1 system PRIMARY NULL NULL NULL 1 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 INSERT INTO t0 VALUES (0); INSERT INTO t1 VALUES (0); SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1; a0 a1 a2 a3 1 1 NULL NULL EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t0 const PRIMARY PRIMARY 4 const 1 Using index 1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 Using index 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 drop table t1,t2; create table t1 (a int, b int); insert into t1 values (1,1),(2,2),(3,3); create table t2 (a int, b int); insert into t2 values (1,1), (2,2); select * from t2 right join t1 on t2.a=t1.a; a b a b 1 1 1 1 2 2 2 2 NULL NULL 3 3 select straight_join * from t2 right join t1 on t2.a=t1.a; a b a b 1 1 1 1 2 2 2 2 NULL NULL 3 3 DROP TABLE t0,t1,t2,t3; CREATE TABLE t1 (a int PRIMARY KEY, b int); CREATE TABLE t2 (a int PRIMARY KEY, b int); INSERT INTO t1 VALUES (1,1), (2,1), (3,1), (4,2); INSERT INTO t2 VALUES (1,2), (2,2); SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a; a b a b 1 1 1 2 2 1 2 2 3 1 NULL NULL 4 2 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a WHERE t1.b=1; a b a b 1 1 1 2 2 1 2 2 3 1 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a WHERE t1.b=1 XOR (NOT ISNULL(t2.a) AND t2.b=1); a b a b 1 1 1 2 2 1 2 2 3 1 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.a WHERE not(0+(t1.a=30 and t2.b=1)); a b a b 1 1 1 2 2 1 2 2 3 1 NULL NULL 4 2 NULL NULL DROP TABLE t1,t2; set group_concat_max_len=5; create table t1 (a int, b varchar(20)); create table t2 (a int, c varchar(20)); insert into t1 values (1,"aaaaaaaaaa"),(2,"bbbbbbbbbb"); insert into t2 values (1,"cccccccccc"),(2,"dddddddddd"); select group_concat(t1.b,t2.c) from t1 left join t2 using(a) group by t1.a; group_concat(t1.b,t2.c) aaaaa bbbbb Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() select group_concat(t1.b,t2.c) from t1 inner join t2 using(a) group by t1.a; group_concat(t1.b,t2.c) aaaaa bbbbb Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() select group_concat(t1.b,t2.c) from t1 left join t2 using(a) group by a; group_concat(t1.b,t2.c) aaaaa bbbbb Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() select group_concat(t1.b,t2.c) from t1 inner join t2 using(a) group by a; group_concat(t1.b,t2.c) aaaaa bbbbb Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() drop table t1, t2; set group_concat_max_len=default; create table t1 (gid smallint(5) unsigned not null, x int(11) not null, y int(11) not null, art int(11) not null, primary key (gid,x,y)); insert t1 values (1, -5, -8, 2), (1, 2, 2, 1), (1, 1, 1, 1); create table t2 (gid smallint(5) unsigned not null, x int(11) not null, y int(11) not null, id int(11) not null, primary key (gid,id,x,y), key id (id)); insert t2 values (1, -5, -8, 1), (1, 1, 1, 1), (1, 2, 2, 1); create table t3 ( set_id smallint(5) unsigned not null, id tinyint(4) unsigned not null, name char(12) not null, primary key (id,set_id)); insert t3 values (0, 1, 'a'), (1, 1, 'b'), (0, 2, 'c'), (1, 2, 'd'), (1, 3, 'e'), (1, 4, 'f'), (1, 5, 'g'), (1, 6, 'h'); explain select name from t1 left join t2 on t1.x = t2.x and t1.y = t2.y left join t3 on t1.art = t3.id where t2.id =1 and t2.x = -5 and t2.y =-8 and t1.gid =1 and t2.gid =1 and t3.set_id =1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 const PRIMARY PRIMARY 10 const,const,const 1 1 SIMPLE t2 const PRIMARY,id PRIMARY 14 const,const,const,const 1 Using index 1 SIMPLE t3 const PRIMARY PRIMARY 3 const,const 1 drop tables t1,t2,t3; CREATE TABLE t1 (EMPNUM INT, GRP INT); INSERT INTO t1 VALUES (0, 10); INSERT INTO t1 VALUES (2, 30); CREATE TABLE t2 (EMPNUM INT, NAME CHAR(5)); INSERT INTO t2 VALUES (0, 'KERI'); INSERT INTO t2 VALUES (9, 'BARRY'); CREATE VIEW v1 AS SELECT COALESCE(t2.EMPNUM,t1.EMPNUM) AS EMPNUM, NAME, GRP FROM t2 LEFT OUTER JOIN t1 ON t2.EMPNUM=t1.EMPNUM; SELECT * FROM v1; EMPNUM NAME GRP 0 KERI 10 9 BARRY NULL SELECT * FROM v1 WHERE EMPNUM < 10; EMPNUM NAME GRP 0 KERI 10 9 BARRY NULL DROP VIEW v1; DROP TABLE t1,t2; CREATE TABLE t1 (c11 int); CREATE TABLE t2 (c21 int); INSERT INTO t1 VALUES (30), (40), (50); INSERT INTO t2 VALUES (300), (400), (500); SELECT * FROM t1 LEFT JOIN t2 ON (c11=c21 AND c21=30) WHERE c11=40; c11 c21 40 NULL DROP TABLE t1, t2; CREATE TABLE t1 (a int PRIMARY KEY, b int); CREATE TABLE t2 (a int PRIMARY KEY, b int); INSERT INTO t1 VALUES (1,2), (2,1), (3,2), (4,3), (5,6), (6,5), (7,8), (8,7), (9,10); INSERT INTO t2 VALUES (3,0), (4,1), (6,4), (7,5); SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.b <= t1.a AND t1.a <= t1.b; a b a b 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a BETWEEN t2.b AND t1.b; a b a b 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a NOT BETWEEN t2.b AND t1.b); a b a b 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.b > t1.a OR t1.a > t1.b; a b a b 2 1 NULL NULL 3 2 3 0 4 3 4 1 6 5 6 4 8 7 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a NOT BETWEEN t2.b AND t1.b; a b a b 2 1 NULL NULL 3 2 3 0 4 3 4 1 6 5 6 4 8 7 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a BETWEEN t2.b AND t1.b); a b a b 2 1 NULL NULL 3 2 3 0 4 3 4 1 6 5 6 4 8 7 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t2.b > t1.a OR t1.a > t1.b; a b a b 2 1 NULL NULL 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 8 7 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a != t2.a AND t1.a BETWEEN t2.b AND t1.b); a b a b 2 1 NULL NULL 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 8 7 NULL NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a AND (t2.b > t1.a OR t1.a > t1.b); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a != t2.a OR t1.a BETWEEN t2.b AND t1.b); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b; a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a NOT IN(t2.a, t2.b)); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a != t1.b AND t1.a != t2.b; a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a NOT IN(t1.b, t2.b); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t1.a IN(t1.b, t2.b)); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.a != t2.b OR (t1.a != t2.a AND t1.a != t2.b); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t2.a = t2.b AND t1.a IN(t2.a, t2.b)); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t2.a != t2.b AND t1.a != t1.b AND t1.a != t2.b; a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE NOT(t2.a = t2.b OR t1.a IN(t1.b, t2.b)); a b a b 3 2 3 0 4 3 4 1 6 5 6 4 7 8 7 5 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4 Using where 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a > IF(t1.a = t2.b-2, t2.b, t2.b-1); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 4 Using where 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.a 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan DROP TABLE t1,t2; DROP VIEW IF EXISTS v1,v2; DROP TABLE IF EXISTS t1,t2; CREATE TABLE t1 (a int); CREATE table t2 (b int); INSERT INTO t1 VALUES (1), (2), (3), (4), (1), (1), (3); INSERT INTO t2 VALUES (2), (3); CREATE VIEW v1 AS SELECT a FROM t1 JOIN t2 ON t1.a=t2.b; CREATE VIEW v2 AS SELECT b FROM t2 JOIN t1 ON t2.b=t1.a; SELECT v1.a, v2. b FROM v1 LEFT OUTER JOIN v2 ON (v1.a=v2.b) AND (v1.a >= 3) GROUP BY v1.a; a b 2 NULL 3 3 SELECT v1.a, v2. b FROM { OJ v1 LEFT OUTER JOIN v2 ON (v1.a=v2.b) AND (v1.a >= 3) } GROUP BY v1.a; a b 2 NULL 3 3 DROP VIEW v1,v2; DROP TABLE t1,t2; CREATE TABLE t1 (a int); CREATE TABLE t2 (b int); INSERT INTO t1 VALUES (1), (2), (3), (4); INSERT INTO t2 VALUES (2), (3); SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1); a b 1 NULL 2 2 3 3 4 NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1 OR 1); a b 1 NULL 2 2 3 3 4 NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (0 OR 1); a b 1 NULL 2 2 3 3 4 NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 2=2); a b 1 NULL 2 2 3 3 4 NULL SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.b WHERE (1=1 OR 1=0); a b 1 NULL 2 2 3 3 4 NULL DROP TABLE t1,t2; CREATE TABLE t1 ( f1 varchar(16) collate latin1_swedish_ci PRIMARY KEY, f2 varchar(16) collate latin1_swedish_ci ); CREATE TABLE t2 ( f1 varchar(16) collate latin1_swedish_ci PRIMARY KEY, f3 varchar(16) collate latin1_swedish_ci ); INSERT INTO t1 VALUES ('bla','blah'); INSERT INTO t2 VALUES ('bla','sheep'); SELECT * FROM t1 JOIN t2 USING(f1) WHERE f1='Bla'; f1 f2 f3 bla blah sheep SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='bla'; f1 f2 f3 bla blah sheep SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='Bla'; f1 f2 f3 bla blah sheep DROP TABLE t1,t2; CREATE TABLE t1 (id int PRIMARY KEY, a varchar(8)); CREATE TABLE t2 (id int NOT NULL, b int NOT NULL, INDEX idx(id)); INSERT INTO t1 VALUES (1,'aaaaaaa'), (5,'eeeeeee'), (4,'ddddddd'), (2,'bbbbbbb'), (3,'ccccccc'); INSERT INTO t2 VALUES (3,10), (2,20), (5,30), (3,20), (5,10), (3,40), (3,30), (2,10), (2,40); EXPLAIN SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 5 1 SIMPLE t2 ref idx idx 4 test.t1.id 2 Using where; Not exists; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan flush status; SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL; id a 1 aaaaaaa 4 ddddddd show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 5 Handler_read_last 0 Handler_read_next 9 Handler_read_prev 0 Handler_read_retry 0 Handler_read_rnd 3 Handler_read_rnd_deleted 0 Handler_read_rnd_next 6 DROP TABLE t1,t2; CREATE TABLE t1 (c int PRIMARY KEY, e int NOT NULL); INSERT INTO t1 VALUES (1,0), (2,1); CREATE TABLE t2 (d int PRIMARY KEY); INSERT INTO t2 VALUES (1), (2), (3); EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 1 SIMPLE t2 index NULL PRIMARY 4 NULL 3 Using where; Using index; Not exists SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL; c e d 1 0 NULL SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d<=>NULL; c e d 1 0 NULL DROP TABLE t1,t2; # # Bug#47650: using group by with rollup without indexes returns incorrect # results with where # CREATE TABLE t1 ( a INT ); INSERT INTO t1 VALUES (1); CREATE TABLE t2 ( a INT, b INT ); INSERT INTO t2 VALUES (1, 1),(1, 2),(1, 3),(2, 4),(2, 5); EXPLAIN SELECT t1.a, COUNT( t2.b ), SUM( t2.b ), MAX( t2.b ) FROM t1 LEFT JOIN t2 USING( a ) GROUP BY t1.a WITH ROLLUP; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 Using temporary; Using filesort 1 SIMPLE t2 ALL NULL NULL NULL NULL 5 Using where SELECT t1.a, COUNT( t2.b ), SUM( t2.b ), MAX( t2.b ) FROM t1 LEFT JOIN t2 USING( a ) GROUP BY t1.a WITH ROLLUP; a COUNT( t2.b ) SUM( t2.b ) MAX( t2.b ) 1 3 6 3 NULL 3 6 3 EXPLAIN SELECT t1.a, COUNT( t2.b ), SUM( t2.b ), MAX( t2.b ) FROM t1 JOIN t2 USING( a ) GROUP BY t1.a WITH ROLLUP; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 1 SIMPLE t2 ALL NULL NULL NULL NULL 5 Using where; Using filesort SELECT t1.a, COUNT( t2.b ), SUM( t2.b ), MAX( t2.b ) FROM t1 JOIN t2 USING( a ) GROUP BY t1.a WITH ROLLUP; a COUNT( t2.b ) SUM( t2.b ) MAX( t2.b ) 1 3 6 3 NULL 3 6 3 DROP TABLE t1, t2; # # Bug#51598 Inconsistent behaviour with a COALESCE statement inside an IN comparison # CREATE TABLE t1(f1 INT, f2 INT, f3 INT); INSERT INTO t1 VALUES (1, NULL, 3); CREATE TABLE t2(f1 INT, f2 INT); INSERT INTO t2 VALUES (2, 1); EXPLAIN EXTENDED SELECT * FROM t1 LEFT JOIN t2 ON t1.f2 = t2.f2 WHERE (COALESCE(t1.f1, t2.f1), f3) IN ((1, 3), (2, 2)); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00 1 SIMPLE t2 system NULL NULL NULL NULL 1 100.00 Warnings: Note 1003 select 1 AS `f1`,NULL AS `f2`,3 AS `f3`,NULL AS `f1`,NULL AS `f2` from `test`.`t2` where 1 SELECT * FROM t1 LEFT JOIN t2 ON t1.f2 = t2.f2 WHERE (COALESCE(t1.f1, t2.f1), f3) IN ((1, 3), (2, 2)); f1 f2 f3 f1 f2 1 NULL 3 NULL NULL DROP TABLE t1, t2; # # Bug#52357: Assertion failed: join->best_read in greedy_search # optimizer_search_depth=0 # CREATE TABLE t1( a INT ); INSERT INTO t1 VALUES (1),(2); SET optimizer_search_depth = 0; # Should not core dump on query preparation EXPLAIN SELECT 1 FROM t1 tt3 LEFT OUTER JOIN t1 tt4 ON 1 LEFT OUTER JOIN t1 tt5 ON 1 LEFT OUTER JOIN t1 tt6 ON 1 LEFT OUTER JOIN t1 tt7 ON 1 LEFT OUTER JOIN t1 tt8 ON 1 RIGHT OUTER JOIN t1 tt2 ON 1 RIGHT OUTER JOIN t1 tt1 ON 1 STRAIGHT_JOIN t1 tt9 ON 1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE tt1 ALL NULL NULL NULL NULL 2 1 SIMPLE tt2 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join) 1 SIMPLE tt3 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt4 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt5 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt6 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt7 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt8 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE tt9 ALL NULL NULL NULL NULL 2 Using join buffer (incremental, BNL join) SET optimizer_search_depth = DEFAULT; DROP TABLE t1; # # Bug#46091 STRAIGHT_JOIN + RIGHT JOIN returns different result # CREATE TABLE t1 (f1 INT NOT NULL); INSERT INTO t1 VALUES (9),(0); CREATE TABLE t2 (f1 INT NOT NULL); INSERT INTO t2 VALUES (5),(3),(0),(3),(1),(0),(1),(7),(1),(0),(0),(8),(4),(9),(0),(2),(0),(8),(5),(1); SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1 RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1; COUNT(*) 476 EXPLAIN SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1 RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE TA2 ALL NULL NULL NULL NULL 20 Using where 1 SIMPLE TA3 ALL NULL NULL NULL NULL 20 Using join buffer (flat, BNL join) 1 SIMPLE TA1 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (incremental, BNL join) DROP TABLE t1, t2; # # Bug#48971 Segfault in add_found_match_trig_cond () at sql_select.cc:5990 # CREATE TABLE t1(f1 INT, PRIMARY KEY (f1)); INSERT INTO t1 VALUES (1),(2); EXPLAIN EXTENDED SELECT STRAIGHT_JOIN jt1.f1 FROM t1 AS jt1 LEFT JOIN t1 AS jt2 RIGHT JOIN t1 AS jt3 JOIN t1 AS jt4 ON 1 LEFT JOIN t1 AS jt5 ON 1 ON 1 RIGHT JOIN t1 AS jt6 ON jt6.f1 ON 1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE jt1 index NULL PRIMARY 4 NULL 2 100.00 Using index 1 SIMPLE jt6 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (flat, BNL join) 1 SIMPLE jt3 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt4 index NULL PRIMARY 4 NULL 2 100.00 Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt5 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt2 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) Warnings: Note 1003 select straight_join `test`.`jt1`.`f1` AS `f1` from `test`.`t1` `jt1` left join (`test`.`t1` `jt6` left join (`test`.`t1` `jt3` join `test`.`t1` `jt4` left join `test`.`t1` `jt5` on(1) left join `test`.`t1` `jt2` on(1)) on(`test`.`jt6`.`f1` <> 0 and 1)) on(1) where 1 EXPLAIN EXTENDED SELECT STRAIGHT_JOIN jt1.f1 FROM t1 AS jt1 RIGHT JOIN t1 AS jt2 RIGHT JOIN t1 AS jt3 JOIN t1 AS jt4 ON 1 LEFT JOIN t1 AS jt5 ON 1 ON 1 RIGHT JOIN t1 AS jt6 ON jt6.f1 ON 1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE jt6 index NULL PRIMARY 4 NULL 2 100.00 Using index 1 SIMPLE jt3 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (flat, BNL join) 1 SIMPLE jt4 index NULL PRIMARY 4 NULL 2 100.00 Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt5 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt2 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) 1 SIMPLE jt1 index NULL PRIMARY 4 NULL 2 100.00 Using where; Using index; Using join buffer (incremental, BNL join) Warnings: Note 1003 select straight_join `test`.`jt1`.`f1` AS `f1` from `test`.`t1` `jt6` left join (`test`.`t1` `jt3` join `test`.`t1` `jt4` left join `test`.`t1` `jt5` on(1) left join `test`.`t1` `jt2` on(1)) on(`test`.`jt6`.`f1` <> 0 and 1) left join `test`.`t1` `jt1` on(1) where 1 DROP TABLE t1; # # Bug#57688 Assertion `!table || (!table->write_set || bitmap_is_set(table->write_set, field # CREATE TABLE t1 (f1 INT NOT NULL, PRIMARY KEY (f1)); CREATE TABLE t2 (f1 INT NOT NULL, f2 INT NOT NULL, PRIMARY KEY (f1, f2)); INSERT INTO t1 VALUES (4); INSERT INTO t2 VALUES (3, 3); INSERT INTO t2 VALUES (7, 7); EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 GROUP BY t2.f1, t2.f2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system PRIMARY NULL NULL NULL 1 Using temporary; Using filesort 1 SIMPLE t2 ref PRIMARY PRIMARY 4 const 1 Using index SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 GROUP BY t2.f1, t2.f2; f1 f1 f2 4 NULL NULL EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 AND t2.f1 IS NOT NULL AND t2.f2 IS NOT NULL GROUP BY t2.f1, t2.f2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system PRIMARY NULL NULL NULL 1 1 SIMPLE t2 ref PRIMARY PRIMARY 4 const 1 Using where; Using index; Using filesort SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 AND t2.f1 IS NOT NULL AND t2.f2 IS NOT NULL GROUP BY t2.f1, t2.f2; f1 f1 f2 DROP TABLE t1,t2; # # Bug#57034 incorrect OUTER JOIN result when joined on unique key # CREATE TABLE t1 (pk INT PRIMARY KEY, col_int INT, col_int_unique INT UNIQUE KEY); INSERT INTO t1 VALUES (1,NULL,2), (2,0,0); CREATE TABLE t2 (pk INT PRIMARY KEY, col_int INT, col_int_unique INT UNIQUE KEY); INSERT INTO t2 VALUES (1,0,1), (2,0,2); EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.col_int_unique = t2.col_int_unique AND t1.col_int = t2.col_int WHERE t1.pk=1; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 1 SIMPLE t2 const col_int_unique col_int_unique 5 const 1 SELECT * FROM t1 LEFT JOIN t2 ON t1.col_int_unique = t2.col_int_unique AND t1.col_int = t2.col_int WHERE t1.pk=1; pk col_int col_int_unique pk col_int col_int_unique 1 NULL 2 NULL NULL NULL DROP TABLE t1,t2; # # Bug#48046 Server incorrectly processing JOINs on NULL values # CREATE TABLE `BB` ( `pk` int(11) NOT NULL AUTO_INCREMENT, `time_key` time DEFAULT NULL, `varchar_key` varchar(1) DEFAULT NULL, `varchar_nokey` varchar(1) DEFAULT NULL, PRIMARY KEY (`pk`), KEY `time_key` (`time_key`), KEY `varchar_key` (`varchar_key`) ) ENGINE=MyISAM AUTO_INCREMENT=11 DEFAULT CHARSET=latin1; INSERT INTO `BB` VALUES (10,'18:27:58',NULL,NULL); SELECT table1.time_key AS field1, table2.pk FROM BB table1 LEFT JOIN BB table2 ON table2.varchar_nokey = table1.varchar_key HAVING field1; field1 pk 18:27:58 NULL DROP TABLE BB; # # Bug#49600 Server incorrectly processing RIGHT JOIN with # constant WHERE clause and no index # CREATE TABLE `BB` ( `col_datetime_key` datetime DEFAULT NULL, `col_varchar_key` varchar(1) DEFAULT NULL, `col_varchar_nokey` varchar(1) DEFAULT NULL, KEY `col_datetime_key` (`col_datetime_key`), KEY `col_varchar_key` (`col_varchar_key`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `BB` VALUES ('1900-01-01 00:00:00',NULL,NULL); SELECT table1.col_datetime_key FROM BB table1 RIGHT JOIN BB table2 ON table2 .col_varchar_nokey = table1.col_varchar_key WHERE 7; col_datetime_key NULL ALTER TABLE BB DISABLE KEYS; SELECT table1.col_datetime_key FROM BB table1 RIGHT JOIN BB table2 ON table2 .col_varchar_nokey = table1.col_varchar_key WHERE 7; col_datetime_key NULL DROP TABLE BB; # # Bug#58490: Incorrect result in multi level OUTER JOIN # in combination with IS NULL # CREATE TABLE t1 (i INT NOT NULL); INSERT INTO t1 VALUES (0), (2),(3),(4); CREATE TABLE t2 (i INT NOT NULL); INSERT INTO t2 VALUES (0),(1), (3),(4); CREATE TABLE t3 (i INT NOT NULL); INSERT INTO t3 VALUES (0),(1),(2), (4); CREATE TABLE t4 (i INT NOT NULL); INSERT INTO t4 VALUES (0),(1),(2),(3) ; SELECT * FROM t1 LEFT JOIN ( t2 LEFT JOIN ( t3 LEFT JOIN t4 ON t4.i = t3.i ) ON t3.i = t2.i ) ON t2.i = t1.i ; i i i i 0 0 0 0 2 NULL NULL NULL 3 3 NULL NULL 4 4 4 NULL SELECT * FROM t1 LEFT JOIN ( t2 LEFT JOIN ( t3 LEFT JOIN t4 ON t4.i = t3.i ) ON t3.i = t2.i ) ON t2.i = t1.i WHERE t4.i IS NULL; i i i i 2 NULL NULL NULL 3 3 NULL NULL 4 4 4 NULL SELECT * FROM t1 LEFT JOIN ( ( t2 LEFT JOIN t3 ON t3.i = t2.i ) ) ON t2.i = t1.i WHERE t3.i IS NULL; i i i 2 NULL NULL 3 3 NULL SELECT * FROM t1 LEFT JOIN ( ( t2 LEFT JOIN t3 ON t3.i = t2.i ) JOIN t4 ON t4.i=t2.i ) ON t2.i = t1.i WHERE t3.i IS NULL; i i i i 2 NULL NULL NULL 3 3 NULL 3 4 NULL NULL NULL SELECT * FROM t1 LEFT JOIN ( ( t2 LEFT JOIN t3 ON t3.i = t2.i ) JOIN (t4 AS t4a JOIN t4 AS t4b ON t4a.i=t4b.i) ON t4a.i=t2.i ) ON t2.i = t1.i WHERE t3.i IS NULL; i i i i i 2 NULL NULL NULL NULL 3 3 NULL 3 3 4 NULL NULL NULL NULL SELECT * FROM t1 LEFT JOIN ( ( t2 LEFT JOIN t3 ON t3.i = t2.i ) JOIN (t4 AS t4a, t4 AS t4b) ON t4a.i=t2.i ) ON t2.i = t1.i WHERE t3.i IS NULL; i i i i i 2 NULL NULL NULL NULL 3 3 NULL 3 0 3 3 NULL 3 1 3 3 NULL 3 2 3 3 NULL 3 3 4 NULL NULL NULL NULL DROP TABLE t1,t2,t3,t4; # # Bug#49322(Duplicate): Server is adding extra NULL row # on processing a WHERE clause # CREATE TABLE h (pk INT NOT NULL, col_int_key INT); INSERT INTO h VALUES (1,NULL),(4,2),(5,2),(3,4),(2,8); CREATE TABLE m (pk INT NOT NULL, col_int_key INT); INSERT INTO m VALUES (1,2),(2,7),(3,5),(4,7),(5,5),(6,NULL),(7,NULL),(8,9); CREATE TABLE k (pk INT NOT NULL, col_int_key INT); INSERT INTO k VALUES (1,9),(2,2),(3,5),(4,2),(5,7),(6,0),(7,5); SELECT TABLE1.pk FROM k TABLE1 RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key; pk 2 2 4 4 NULL NULL NULL NULL NULL NULL NULL SELECT TABLE1.pk FROM k TABLE1 RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key WHERE TABLE1.pk IS NULL; pk NULL NULL NULL NULL NULL NULL NULL DROP TABLE h,m,k; # BUG#12567331 - INFINITE LOOP WHEN RESOLVING AN ALIASED COLUMN # USED IN GROUP BY CREATE TABLE t1 ( col_varchar_1024_latin1_key varchar(1024), col_varchar_10_latin1 varchar(10), col_int int(11), pk int(11) ); CREATE TABLE t2 ( col_int_key int(11), col_int int(11), pk int(11) ); PREPARE prep_stmt_9846 FROM ' SELECT alias1.pk AS field1 FROM t1 AS alias1 LEFT JOIN ( t2 AS alias2 RIGHT JOIN ( t2 AS alias3 JOIN t1 AS alias4 ON 1 ) ON 1 ) ON 1 GROUP BY field1'; execute prep_stmt_9846; field1 execute prep_stmt_9846; field1 drop table t1,t2; # # Bug #11765810 58813: SERVER THREAD HANGS WHEN JOIN + WHERE + GROUP BY # IS EXECUTED TWICE FROM P # CREATE TABLE t1 ( a INT ) ENGINE = MYISAM; INSERT INTO t1 VALUES (1); PREPARE prep_stmt FROM ' SELECT 1 AS f FROM t1 LEFT JOIN t1 t2 RIGHT JOIN t1 t3 JOIN t1 t4 ON 1 ON 1 ON 1 GROUP BY f'; EXECUTE prep_stmt; f 1 EXECUTE prep_stmt; f 1 DROP TABLE t1; # # Bug#49600: outer join of two single-row tables with joining attributes # evaluated to nulls create table t1 (a int, b int); create table t2 (a int, b int); insert into t1 values (1, NULL); insert into t2 values (2, NULL); select * from t1 left join t2 on t1.b=t2.b; a b a b 1 NULL NULL NULL select * from t1 left join t2 on t1.b=t2.b where 1=1; a b a b 1 NULL NULL NULL drop table t1,t2; # # Bug#53161: outer join in the derived table is erroneously converted # into an inner join for a query with a group by clause # create table t1 (pk int not null primary key, a int not null); create table t2 like t1; create table t3 like t1; create table t4 (pk int not null primary key); insert into t1 values (1000, 1), (1001, 1); insert into t2 values (2000, 2), (2001, 2); insert into t3 values (3000, 3), (3001, 2); insert into t4 values (4000), (4001); explain extended select t2.pk, (select t3.pk+if(isnull(t4.pk),0,t4.pk) from t3 left join t4 on t4.pk=t3.pk where t3.pk=t2.pk+1000 limit 1 ) as t from t1,t2 where t2.pk=t1.pk+1000 and t1.pk>1000 group by t2.pk; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 index PRIMARY PRIMARY 4 NULL 2 100.00 Using where; Using index; Using temporary; Using filesort 1 PRIMARY t2 eq_ref PRIMARY PRIMARY 4 func 1 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t3 eq_ref PRIMARY PRIMARY 4 func 1 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t4 eq_ref PRIMARY PRIMARY 4 test.t3.pk 1 100.00 Using index Warnings: Note 1276 Field or reference 'test.t2.pk' of SELECT #2 was resolved in SELECT #1 Note 1003 /* select#1 */ select `test`.`t2`.`pk` AS `pk`,<`test`.`t2`.`pk`>((/* select#2 */ select `test`.`t3`.`pk` + if(`test`.`t4`.`pk` is null,0,`test`.`t4`.`pk`) from `test`.`t3` left join `test`.`t4` on(`test`.`t4`.`pk` = `test`.`t3`.`pk`) where `test`.`t3`.`pk` = `test`.`t2`.`pk` + 1000 limit 1)) AS `t` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`pk` = `test`.`t1`.`pk` + 1000 and `test`.`t1`.`pk` > 1000 group by `test`.`t2`.`pk` select t2.pk, (select t3.pk+if(isnull(t4.pk),0,t4.pk) from t3 left join t4 on t4.pk=t3.pk where t3.pk=t2.pk+1000 limit 1 ) as t from t1,t2 where t2.pk=t1.pk+1000 and t1.pk>1000 group by t2.pk; pk t 2001 3001 drop table t1,t2,t3,t4; # # Bug#57024: Poor performance when conjunctive condition over the outer # table is used in the on condition of an outer join # create table t1 (a int); insert into t1 values (NULL), (NULL), (NULL), (NULL); insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 select * from t1; insert into t1 values (4), (2), (1), (3); create table t2 like t1; insert into t2 select if(t1.a is null, 10, t1.a) from t1; create table t3 (a int, b int, index idx(a)); insert into t3 values (1, 100), (3, 301), (4, 402), (1, 102), (1, 101); insert into t3 values (11, 100), (33, 301), (44, 402), (11, 102), (11, 101); insert into t3 values (22, 100), (53, 301), (64, 402), (22, 102), (22, 101); analyze table t1,t2,t3; Table Op Msg_type Msg_text test.t1 analyze status OK test.t2 analyze status OK test.t3 analyze status OK flush status; select sum(t3.b) from t1 left join t3 on t3.a=t1.a and t1.a is not null; sum(t3.b) 1006 show status like "handler_read%"; Variable_name Value Handler_read_first 0 Handler_read_key 4 Handler_read_last 0 Handler_read_next 5 Handler_read_prev 0 Handler_read_retry 0 Handler_read_rnd 5 Handler_read_rnd_deleted 0 Handler_read_rnd_next 1048581 flush status; select sum(t3.b) from t2 left join t3 on t3.a=t2.a and t2.a <> 10; sum(t3.b) 1006 show status like "handler_read%"; Variable_name Value Handler_read_first 0 Handler_read_key 4 Handler_read_last 0 Handler_read_next 5 Handler_read_prev 0 Handler_read_retry 0 Handler_read_rnd 5 Handler_read_rnd_deleted 0 Handler_read_rnd_next 1048581 drop table t1,t2,t3; # # Bug#57688 Assertion `!table || (!table->write_set || bitmap_is_set(table->write_set, field # CREATE TABLE t1 (f1 INT NOT NULL, PRIMARY KEY (f1)); CREATE TABLE t2 (f1 INT NOT NULL, f2 INT NOT NULL, PRIMARY KEY (f1, f2)); INSERT INTO t1 VALUES (4); INSERT INTO t2 VALUES (3, 3); INSERT INTO t2 VALUES (7, 7); EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 GROUP BY t2.f1, t2.f2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system PRIMARY NULL NULL NULL 1 Using temporary; Using filesort 1 SIMPLE t2 ref PRIMARY PRIMARY 4 const 1 Using index SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 GROUP BY t2.f1, t2.f2; f1 f1 f2 4 NULL NULL EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 AND t2.f1 IS NOT NULL AND t2.f2 IS NOT NULL GROUP BY t2.f1, t2.f2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 system PRIMARY NULL NULL NULL 1 1 SIMPLE t2 ref PRIMARY PRIMARY 4 const 1 Using where; Using index; Using filesort SELECT * FROM t1 LEFT JOIN t2 ON t2.f1 = t1.f1 WHERE t1.f1 = 4 AND t2.f1 IS NOT NULL AND t2.f2 IS NOT NULL GROUP BY t2.f1, t2.f2; f1 f1 f2 DROP TABLE t1,t2; # # Bug#13068506 - QUERY WITH GROUP BY ON NON-AGGR COLUMN RETURNS # WRONG RESULT # CREATE TABLE t1 (i1 int); INSERT INTO t1 VALUES (100), (101); CREATE TABLE t2 (i2 int, i3 int); INSERT INTO t2 VALUES (20,1),(10,2); CREATE TABLE t3 (i4 int(11)); INSERT INTO t3 VALUES (1),(2); SELECT ( SELECT MAX( t2.i2 ) FROM t3 RIGHT JOIN t2 ON ( t2.i3 = 2 ) WHERE t2.i3 <> t1.i1 ) AS field1 FROM t1;; field1 20 20 SELECT ( SELECT MAX( t2.i2 ) FROM t3 RIGHT JOIN t2 ON ( t2.i3 = 2 ) WHERE t2.i3 <> t1.i1 ) AS field1 FROM t1 GROUP BY field1;; field1 20 drop table t1,t2,t3; # End of test for Bug#13068506 End of 5.1 tests # # LP BUG#994392: Wrong result with RIGHT/LEFT JOIN and ALL subquery # predicate in WHERE condition. # CREATE TABLE t1(a INT); INSERT INTO t1 VALUES(9); CREATE TABLE t2(b INT); INSERT INTO t2 VALUES(8); CREATE TABLE t3(c INT); INSERT INTO t3 VALUES(3); SELECT * FROM t2 RIGHT JOIN t3 ON(c = b) WHERE b < ALL(SELECT a FROM t1 WHERE a <= 7); b c NULL 3 SELECT * FROM t3 LEFT JOIN t2 ON(c = b) WHERE b < ALL(SELECT a FROM t1 WHERE a <= 7); c b 3 NULL SELECT * FROM t2 RIGHT JOIN t3 ON(c = b) WHERE b not in (SELECT a FROM t1 WHERE a <= 7); b c NULL 3 SELECT * FROM t3 LEFT JOIN t2 ON(c = b) WHERE b not in (SELECT a FROM t1 WHERE a <= 7); c b 3 NULL drop table t1,t2,t3; End of 5.2 tests # # LP bug #813447: LEFT JOIN with single-row inner table and # a subquery in ON expression # CREATE TABLE t1 (a int); INSERT INTO t1 VALUES (0); CREATE TABLE t2 (a int); INSERT INTO t2 VALUES (0); CREATE TABLE t3 (a int); INSERT INTO t3 VALUES (0), (0); SELECT t2.a FROM t1 LEFT JOIN t2 ON (6) IN (SELECT a FROM t3); a NULL EXPLAIN EXTENDED SELECT t2.a FROM t1 LEFT JOIN t2 ON (6) IN (SELECT a FROM t3); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 100.00 1 PRIMARY t2 system NULL NULL NULL NULL 1 100.00 2 SUBQUERY t3 ALL NULL NULL NULL NULL 2 100.00 Using where Warnings: Note 1003 /* select#1 */ select NULL AS `a` from `test`.`t2` where 1 DROP TABLE t1,t2,t3; # # LP bug #817384 Wrong result with outer join + subquery in ON # clause +unique key # CREATE TABLE t1 ( c int NOT NULL , b char(1) NOT NULL ) ; INSERT INTO t1 VALUES (1,'b'); CREATE TABLE t2 ( a int NOT NULL , b char(1) NOT NULL , PRIMARY KEY (a)) ; INSERT INTO t2 VALUES (1,'a'); create table t3 (c1 char(1), c2 char(2)); insert into t3 values ('c','d'); insert into t3 values ('c','d'); EXPLAIN SELECT t2.b FROM t1 LEFT JOIN t2 ON t1.c = t2.a AND ( t2.b , t1.b ) IN (SELECT * from t3); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 1 PRIMARY t2 eq_ref PRIMARY PRIMARY 4 const 1 Using where 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 2 Using where SELECT t2.b FROM t1 LEFT JOIN t2 ON t1.c = t2.a AND ( t2.b , t1.b ) IN (SELECT * from t3); b NULL EXPLAIN SELECT t2.b FROM t1 LEFT JOIN t2 ON (t2.b) IN (SELECT c2 from t3) AND t2.a = 1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 1 PRIMARY t2 const PRIMARY PRIMARY 4 const 1 Using where 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 2 Using where SELECT t2.b FROM t1 LEFT JOIN t2 ON (t2.b) IN (SELECT c2 from t3) AND t2.a = 1; b NULL DROP TABLE t1,t2,t3; # # lp:825035 second execution of PS with outer join # CREATE TABLE t1 (a int); INSERT INTO t1 VALUES (1),(2),(3),(4); CREATE TABLE t2 (a int); PREPARE stmt FROM "SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a"; EXECUTE stmt; a a 1 NULL 2 NULL 3 NULL 4 NULL EXECUTE stmt; a a 1 NULL 2 NULL 3 NULL 4 NULL DEALLOCATE PREPARE stmt; DROP TABLE t1,t2; # # lp:838633 second execution of PS with outer join # converted to inner join # CREATE TABLE t1 ( b int NOT NULL ) ; INSERT INTO t1 VALUES (9),(10); CREATE TABLE t2 ( b int NOT NULL, PRIMARY KEY (b)) ; INSERT INTO t2 VALUES (75),(76),(77),(78),(79),(80),(81),(82),(83),(84),(85),(86),(87),(88),(89), (10), (90),(91),(92),(93),(94),(95),(96),(97),(98),(99),(100); CREATE TABLE t3 ( a int, b int NOT NULL , PRIMARY KEY (b)) ; INSERT INTO t3 VALUES (0,6),(0,7),(0,8),(2,9),(0,10),(2,21),(0,22),(2,23),(2,24),(2,25); SET SESSION join_cache_level=4; EXPLAIN EXTENDED SELECT * FROM (t2 LEFT JOIN t1 ON t1.b = t2.b) JOIN t3 ON t1.b = t3.b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t3 hash_ALL PRIMARY #hash#PRIMARY 4 test.t1.b 10 10.00 Using join buffer (flat, BNLH join) 1 SIMPLE t2 hash_index PRIMARY #hash#PRIMARY:PRIMARY 4:4 test.t1.b 27 3.70 Using index; Using join buffer (incremental, BNLH join) Warnings: Note 1003 select `test`.`t2`.`b` AS `b`,`test`.`t1`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t2` join `test`.`t1` join `test`.`t3` where `test`.`t3`.`b` = `test`.`t1`.`b` and `test`.`t2`.`b` = `test`.`t1`.`b` PREPARE stmt FROM 'SELECT * FROM (t2 LEFT JOIN t1 ON t1.b = t2.b) JOIN t3 ON t1.b = t3.b'; EXECUTE stmt; b b a b 10 10 0 10 EXECUTE stmt; b b a b 10 10 0 10 DEALLOCATE PREPARE stmt; SET SESSION join_cache_level=default; DROP TABLE t1,t2,t3; # # LP bug #943543: LEFT JOIN converted to JOIN with # ORed IS NULL(primary key) in WHERE clause # CREATE TABLE t1 ( a int, b int NOT NULL, pk int NOT NULL, PRIMARY KEY (pk), INDEX idx(b) ); INSERT INTO t1 VALUES (NULL,1,1), (6,2,2), (5,3,3), (NULL,4,4), (1,9,6), (8,5,7), (NULL,8,8), (8,1,5); CREATE TABLE t2 (pk int PRIMARY KEY); INSERT INTO t2 VALUES (3), (8), (5); EXPLAIN EXTENDED SELECT t1.pk FROM t2 JOIN t1 ON t2.pk = t1.a WHERE t1.b BETWEEN 5 AND 6 AND t1.pk IS NULL OR t1.pk = 5 ORDER BY t1.pk; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 100.00 1 SIMPLE t2 const PRIMARY PRIMARY 4 const 1 100.00 Using index Warnings: Note 1003 select 5 AS `pk` from `test`.`t2` join `test`.`t1` where 1 order by 5 SELECT t1.pk FROM t2 JOIN t1 ON t2.pk = t1.a WHERE t1.b BETWEEN 5 AND 6 AND t1.pk IS NULL OR t1.pk = 5 ORDER BY t1.pk; pk 5 EXPLAIN EXTENDED SELECT t1.pk FROM t2 LEFT JOIN t1 ON t2.pk = t1.a WHERE t1.b BETWEEN 5 AND 6 AND t1.pk IS NULL OR t1.pk = 5 ORDER BY t1.pk; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 const PRIMARY,idx PRIMARY 4 const 1 100.00 1 SIMPLE t2 const PRIMARY PRIMARY 4 const 1 100.00 Using index Warnings: Note 1003 select 5 AS `pk` from `test`.`t2` join `test`.`t1` where 1 order by 5 SELECT t1.pk FROM t2 LEFT JOIN t1 ON t2.pk = t1.a WHERE t1.b BETWEEN 5 AND 6 AND t1.pk IS NULL OR t1.pk = 5 ORDER BY t1.pk; pk 5 DROP TABLE t2; CREATE TABLE t2 (c int, d int, KEY (c)); INSERT INTO t2 VALUES (3,30), (8,88), (5,50), (8,81), (4,40), (9,90), (7,70), (9,90), (13,130), (18,188), (15,150), (18,181), (14,140), (19,190), (17,170), (19,190); INSERT INTO t1 VALUES (8,5,9); EXPLAIN EXTENDED SELECT t1.b, t2.c, t2.d FROM t2 JOIN t1 ON t2.c = t1.a WHERE t1.pk BETWEEN 5 AND 6 AND t1.b IS NULL OR t1.b = 5 ORDER BY t1.b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ref idx idx 4 const 2 100.00 Using where 1 SIMPLE t2 ref c c 5 test.t1.a 2 100.00 Warnings: Note 1003 select `test`.`t1`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` join `test`.`t1` where `test`.`t2`.`c` = `test`.`t1`.`a` and `test`.`t1`.`b` = 5 order by `test`.`t1`.`b` SELECT t1.b, t2.c, t2.d FROM t2 JOIN t1 ON t2.c = t1.a WHERE t1.pk BETWEEN 5 AND 6 AND t1.b IS NULL OR t1.b = 5 ORDER BY t1.b; b c d 5 8 88 5 8 81 5 8 88 5 8 81 EXPLAIN EXTENDED SELECT t1.b, t2.c, t2.d FROM t2 LEFT JOIN t1 ON t2.c = t1.a WHERE t1.pk BETWEEN 5 AND 6 AND t1.b IS NULL OR t1.b = 5 ORDER BY t1.b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ref PRIMARY,idx idx 4 const 2 100.00 Using where 1 SIMPLE t2 ref c c 5 test.t1.a 2 100.00 Warnings: Note 1003 select `test`.`t1`.`b` AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2` join `test`.`t1` where `test`.`t2`.`c` = `test`.`t1`.`a` and `test`.`t1`.`b` = 5 order by `test`.`t1`.`b` SELECT t1.b, t2.c, t2.d FROM t2 LEFT JOIN t1 ON t2.c = t1.a WHERE t1.pk BETWEEN 5 AND 6 AND t1.b IS NULL OR t1.b = 5 ORDER BY t1.b; b c d 5 8 88 5 8 81 5 8 88 5 8 81 DROP TABLE t1,t2; # # Bug mdev-4336: LEFT JOIN with disjunctive # IS NULL in WHERE # causes a hang and eventual crash # CREATE TABLE t1 ( id int(11) NOT NULL, modified datetime NOT NULL, PRIMARY KEY (id) ); SELECT a.* FROM t1 a LEFT JOIN t1 b ON a.id = b.id WHERE a.modified > b.modified or b.modified IS NULL; id modified DROP TABLE t1; # # MDEV-4817: Optimizer fails to optimize expression of the form 'FOO' IS NULL # create table t0 (a int not null); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); alter table t0 add person_id varchar(255) not null; create table t1 (pk int not null primary key); insert into t1 select A.a + 10*B.a from t0 A, t0 B; explain select * from t1 left join t0 on t0.a=t1.pk where t0.person_id='fooo' or 'xyz' IS NULL; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t0.a 1 Using index explain select * from t1 left join t0 on t0.a=t1.pk where t0.person_id='fooo'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t0.a 1 Using index explain select * from t1 left join t0 on t0.a=t1.pk where t0.person_id='fooo' or t0.person_id='bar'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t0.a 1 Using index drop table t0, t1; # # MDEV-4836: Wrong result on IS NULL (old documented hack stopped working) # (this is a regression after fix for MDEV-4817) # CREATE TABLE t1 (id INT, d DATE NOT NULL); INSERT INTO t1 VALUES (1,'0000-00-00'),(2,'0000-00-00'); CREATE TABLE t2 (i INT); SELECT * FROM t1 LEFT JOIN t2 ON (id=i) WHERE NULL OR d IS NULL; id d i 1 0000-00-00 NULL 2 0000-00-00 NULL DROP TABLE t1,t2; CREATE TABLE t1 (i1 INT, d1 DATE NOT NULL); INSERT INTO t1 VALUES (1,'2012-12-21'),(2,'0000-00-00'); CREATE TABLE t2 (i2 INT, j2 INT); INSERT INTO t2 VALUES (1,10),(2,20); SELECT * FROM t1 LEFT JOIN t2 ON i1 = j2 WHERE d1 IS NULL AND 1 OR i1 = i2; i1 d1 i2 j2 2 0000-00-00 NULL NULL DROP TABLE t1,t2; # Another testcase CREATE TABLE t1 (i1 INT) ENGINE=MyISAM; INSERT INTO t1 VALUES (NULL); CREATE TABLE t2 (i2 INT, a INT, b INT) ENGINE=MyISAM; CREATE ALGORITHM=TEMPTABLE VIEW v2 AS SELECT * FROM t2; INSERT INTO t2 VALUES (NULL,1,2),(NULL,2,3); SELECT * FROM t1 LEFT JOIN v2 ON i1 = i2 WHERE a < b; i1 i2 a b SELECT * FROM t1 LEFT JOIN t2 ON i1 = i2 WHERE a < b; i1 i2 a b drop view v2; drop table t1,t2; # # Bug mdev-4942: LEFT JOIN with conjunctive # IS NULL in WHERE # causes an assert failure # CREATE TABLE t1 ( i1 int, d1 date ); INSERT INTO t1 VALUES (1,'2001-06-26'), (2,'2000-11-16'); CREATE TABLE t2 ( i2 int, d2 date NOT NULL ); INSERT INTO t2 VALUES (3,'2000-03-06'), (4,'2007-09-25'); SELECT * FROM t1 LEFT JOIN t2 ON i1 = i2 WHERE d1 IS NULL AND d2 IS NULL; i1 d1 i2 d2 DROP TABLE t1,t2; # # Bug mdev-4952: LEFT JOIN with disjunctive # IS NULL in WHERE # causes an assert failure # CREATE TABLE t1 (a1 int, b1 int NOT NULL) ENGINE=MyISAM; INSERT INTO t1 VALUES (1, 10), (2, 11); CREATE TABLE t2 (dt datetime NOT NULL, a2 int, b2 int) ENGINE=MyISAM; INSERT INTO t2 VALUES ('2006-10-08 09:34:54', 1, 100), ('2001-01-19 01:04:43', 2, 200); SELECT * FROM t1 LEFT JOIN t2 ON a1 = a2 WHERE ( dt IS NULL OR FALSE ) AND b2 IS NULL; a1 b1 dt a2 b2 DROP TABLE t1,t2; # # Bug mdev-4962: nested outer join with # IS NULL in WHERE # causes an assert failure # CREATE TABLE t1 (i1 int) ENGINE=MyISAM; INSERT INTO t1 VALUES (1),(2); CREATE TABLE t2 (i2 int) ENGINE=MyISAM; INSERT INTO t2 VALUES (10),(20); CREATE TABLE t3 (i3 int, d3 datetime NOT NULL) ENGINE=MyISAM; INSERT INTO t3 VALUES (8,'2008-12-04 17:53:42'),(9,'2012-12-21 12:12:12'); SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON i2 = i3 ON i1 = i3 WHERE d3 IS NULL; i1 i2 i3 d3 1 NULL NULL NULL 2 NULL NULL NULL EXPLAIN EXTENDED SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON i2 = i3 ON i1 = i3 WHERE d3 IS NULL; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t1`.`i1` AS `i1`,`test`.`t2`.`i2` AS `i2`,`test`.`t3`.`i3` AS `i3`,`test`.`t3`.`d3` AS `d3` from `test`.`t1` left join (`test`.`t2` join `test`.`t3`) on(`test`.`t2`.`i2` = `test`.`t1`.`i1` and `test`.`t3`.`i3` = `test`.`t1`.`i1`) where `test`.`t3`.`d3` = 0 or `test`.`t3`.`d3` is null DROP TABLE t1,t2,t3; # # Bug mdev-6705: wrong on expression after constant row substitution # that triggers a simplification of WHERE condition # CREATE TABLE t1 (a int, b int) ENGINE=MyISAM; INSERT INTO t1 VALUES (10,8); CREATE TABLE t2 (c int) ENGINE=MyISAM; INSERT INTO t2 VALUES (8),(9); CREATE TABLE t3 (d int) ENGINE=MyISAM; INSERT INTO t3 VALUES (3),(8); EXPLAIN EXTENDED SELECT * FROM t1 INNER JOIN t2 ON c = b LEFT JOIN t3 ON d = a WHERE b IN (1,2,3) OR b = d; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select 10 AS `a`,8 AS `b`,`test`.`t2`.`c` AS `c`,`test`.`t3`.`d` AS `d` from `test`.`t2` left join `test`.`t3` on(`test`.`t3`.`d` = 10) where `test`.`t2`.`c` = 8 and `test`.`t3`.`d` = 8 SELECT * FROM t1 INNER JOIN t2 ON c = b LEFT JOIN t3 ON d = a WHERE b IN (1,2,3) OR b = d; a b c d DROP TABLE t1,t2,t3; # # MDEV-6634: Wrong estimates for ref(const) and key IS NULL predicate # create table t1(a int); insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t2 (a int, b int, c int, key(b), key(c)); insert into t2 select @a:=A.a + 10*B.a+100*C.a, IF(@a<900, NULL, @a), IF(@a<500, NULL, @a) from t1 A, t1 B, t1 C; delete from t1 where a=0; # Check that there are different #rows of NULLs for b and c, both !=10: explain select * from t2 force index (b) where b is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ref b b 5 const 780 Using index condition explain select * from t2 force index (c) where c is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ref c c 5 const 393 Using index condition explain select * from t1 left join t2 on t2.b is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 9 1 SIMPLE t2 ref b b 5 const 780 Using where explain select * from t1 left join t2 on t2.c is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 9 1 SIMPLE t2 ref c c 5 const 393 Using where drop table t1,t2; # # MDEV-10006: optimizer doesn't convert outer join to inner on views with WHERE clause # CREATE TABLE t1(i1 int primary key, v1 int, key(v1)); INSERT INTO t1 VALUES (1, 1); INSERT INTO t1 VALUES (2, 2); INSERT INTO t1 VALUES (3, 3); INSERT INTO t1 VALUES (4, 4); INSERT INTO t1 VALUES (5, 3); INSERT INTO t1 VALUES (6, 6); INSERT INTO t1 VALUES (7, 7); INSERT INTO t1 VALUES (8, 8); INSERT INTO t1 VALUES (9, 9); CREATE TABLE t2(i2 int primary key, v2 int, key(v2)); INSERT INTO t2 VALUES (1, 1); INSERT INTO t2 VALUES (2, 2); INSERT INTO t2 VALUES (3, 3); INSERT INTO t2 VALUES (4, 4); INSERT INTO t2 VALUES (5, 3); INSERT INTO t2 VALUES (6, 6); INSERT INTO t2 VALUES (7, 7); INSERT INTO t2 VALUES (8, 8); INSERT INTO t2 VALUES (9, 9); CREATE TABLE t3(i3 int primary key, v3 int, key(v3)); INSERT INTO t3 VALUES (2, 2); INSERT INTO t3 VALUES (4, 4); INSERT INTO t3 VALUES (6, 6); INSERT INTO t3 VALUES (8, 8); # This should have a join order of t3,t1,t2 (or t3,t2,t1, the idea is that t3 is the first one) EXPLAIN EXTENDED SELECT * FROM (SELECT t1.i1 as i1, t1.v1 as v1, t2.i2 as i2, t2.v2 as v2, t3.i3 as i3, t3.v3 as v3 FROM t1 JOIN t2 on t1.i1 = t2.i2 LEFT JOIN t3 on t2.i2 = t3.i3 ) as w1 WHERE v3 = 4; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t3 ref PRIMARY,v3 v3 5 const 1 100.00 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t3.i3 1 100.00 1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t3.i3 1 100.00 Warnings: Note 1003 select `test`.`t1`.`i1` AS `i1`,`test`.`t1`.`v1` AS `v1`,`test`.`t2`.`i2` AS `i2`,`test`.`t2`.`v2` AS `v2`,`test`.`t3`.`i3` AS `i3`,`test`.`t3`.`v3` AS `v3` from `test`.`t1` join `test`.`t2` join `test`.`t3` where `test`.`t3`.`v3` = 4 and `test`.`t1`.`i1` = `test`.`t3`.`i3` and `test`.`t2`.`i2` = `test`.`t3`.`i3` # This should have the same join order like the query above: EXPLAIN EXTENDED SELECT * FROM (SELECT t1.i1 as i1, t1.v1 as v1, t2.i2 as i2, t2.v2 as v2, t3.i3 as i3, t3.v3 as v3 FROM t1 JOIN t2 on t1.i1 = t2.i2 LEFT JOIN t3 on t2.i2 = t3.i3 WHERE t1.i1 = t2.i2 AND 1 = 1 ) as w2 WHERE v3 = 4; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t3 ref PRIMARY,v3 v3 5 const 1 100.00 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t3.i3 1 100.00 1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t3.i3 1 100.00 Warnings: Note 1003 select `test`.`t1`.`i1` AS `i1`,`test`.`t1`.`v1` AS `v1`,`test`.`t2`.`i2` AS `i2`,`test`.`t2`.`v2` AS `v2`,`test`.`t3`.`i3` AS `i3`,`test`.`t3`.`v3` AS `v3` from `test`.`t1` join `test`.`t2` join `test`.`t3` where `test`.`t3`.`v3` = 4 and `test`.`t1`.`i1` = `test`.`t3`.`i3` and `test`.`t2`.`i2` = `test`.`t3`.`i3` drop table t1,t2,t3; # # MDEV-11958: LEFT JOIN with stored routine produces incorrect result # CREATE TABLE t (x INT); INSERT INTO t VALUES(1),(NULL); CREATE FUNCTION f (val INT, ret INT) RETURNS INT DETERMINISTIC RETURN IFNULL(val, ret); SELECT t1.x, t2.x, IFNULL(t2.x,0), f(t2.x,0) FROM t t1 LEFT JOIN t t2 ON t1.x = t2.x WHERE IFNULL(t2.x,0)=0; x x IFNULL(t2.x,0) f(t2.x,0) NULL NULL 0 0 explain extended SELECT t1.x, t2.x, IFNULL(t2.x,0), f(t2.x,0) FROM t t1 LEFT JOIN t t2 ON t1.x = t2.x WHERE IFNULL(t2.x,0)=0; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`x` AS `x`,`test`.`t2`.`x` AS `x`,ifnull(`test`.`t2`.`x`,0) AS `IFNULL(t2.x,0)`,`f`(`test`.`t2`.`x`,0) AS `f(t2.x,0)` from `test`.`t` `t1` left join `test`.`t` `t2` on(`test`.`t2`.`x` = `test`.`t1`.`x`) where ifnull(`test`.`t2`.`x`,0) = 0 SELECT t1.x, t2.x, IFNULL(t2.x,0), f(t2.x,0) FROM t t1 LEFT JOIN t t2 ON t1.x = t2.x WHERE f(t2.x,0)=0; x x IFNULL(t2.x,0) f(t2.x,0) NULL NULL 0 0 explain extended SELECT t1.x, t2.x, IFNULL(t2.x,0), f(t2.x,0) FROM t t1 LEFT JOIN t t2 ON t1.x = t2.x WHERE f(t2.x,0)=0; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`x` AS `x`,`test`.`t2`.`x` AS `x`,ifnull(`test`.`t2`.`x`,0) AS `IFNULL(t2.x,0)`,`f`(`test`.`t2`.`x`,0) AS `f(t2.x,0)` from `test`.`t` `t1` left join `test`.`t` `t2` on(`test`.`t2`.`x` = `test`.`t1`.`x`) where `f`(`test`.`t2`.`x`,0) = 0 drop function f; drop table t; CREATE TABLE t1 ( col1 DECIMAL(33,5) NULL DEFAULT NULL, col2 DECIMAL(33,5) NULL DEFAULT NULL ); CREATE TABLE t2 ( col1 DECIMAL(33,5) NULL DEFAULT NULL, col2 DECIMAL(33,5) NULL DEFAULT NULL, col3 DECIMAL(33,5) NULL DEFAULT NULL ); INSERT INTO t1 VALUES (2, 1.1), (2, 2.1); INSERT INTO t2 VALUES (3, 3.1, 4), (1, 1, NULL); CREATE FUNCTION f1 ( p_num DECIMAL(45,15), p_return DECIMAL(45,15)) RETURNS decimal(33,5) LANGUAGE SQL DETERMINISTIC CONTAINS SQL SQL SECURITY INVOKER BEGIN IF p_num IS NULL THEN RETURN p_return; ELSE RETURN p_num; END IF; END | SELECT t1.col1, t2.col1, t2.col3 FROM t1 LEFT OUTER JOIN t2 ON t1.col1 = t2.col2 WHERE IFNULL(t2.col3,0) = 0; col1 col1 col3 2.00000 NULL NULL 2.00000 NULL NULL EXPLAIN EXTENDED SELECT t1.col1, t2.col1, t2.col3 FROM t1 LEFT OUTER JOIN t2 ON t1.col1 = t2.col2 WHERE IFNULL(t2.col3,0) = 0; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`col1` AS `col1`,`test`.`t2`.`col1` AS `col1`,`test`.`t2`.`col3` AS `col3` from `test`.`t1` left join `test`.`t2` on(`test`.`t2`.`col2` = `test`.`t1`.`col1`) where ifnull(`test`.`t2`.`col3`,0) = 0 SELECT t1.col1, t2.col1, t2.col3 FROM t1 LEFT OUTER JOIN t2 ON t1.col1 = t2.col2 WHERE f1(t2.col3,0) = 0; col1 col1 col3 2.00000 NULL NULL 2.00000 NULL NULL EXPLAIN EXTENDED SELECT t1.col1, t2.col1, t2.col3 FROM t1 LEFT OUTER JOIN t2 ON t1.col1 = t2.col2 WHERE f1(t2.col3,0) = 0; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`col1` AS `col1`,`test`.`t2`.`col1` AS `col1`,`test`.`t2`.`col3` AS `col3` from `test`.`t1` left join `test`.`t2` on(`test`.`t2`.`col2` = `test`.`t1`.`col1`) where `f1`(`test`.`t2`.`col3`,0) = 0 DROP FUNCTION f1; DROP TABLE t1,t2; # # MDEV-10397: Server crashes in key_copy with join_cache_level > 2 and join on BIT fields # CREATE TABLE t1 (b1 BIT NOT NULL); INSERT INTO t1 VALUES (0),(1); CREATE TABLE t2 (b2 BIT NOT NULL); INSERT INTO t2 VALUES (0),(1); set @save_join_cache_level= @@join_cache_level; SET @@join_cache_level = 3; SELECT t1.b1+'0' , t2.b2 + '0' FROM t1 LEFT JOIN t2 ON b1 = b2; t1.b1+'0' t2.b2 + '0' 0 0 1 1 DROP TABLE t1, t2; set @join_cache_level= @save_join_cache_level; # # MDEV-14779: using left join causes incorrect results with materialization and derived tables # create table t1(id int); insert into t1 values (1),(2); create table t2(sid int, id int); insert into t2 values (1,1),(2,2); select * from t1 t left join (select * from t2 where sid in (select max(sid) from t2 where 0=1 group by id)) r on t.id=r.id ; id sid id 1 NULL NULL 2 NULL NULL drop table t1, t2; # # MDEV-16726: SELECT with STRAGHT JOIN containing NESTED RIGHT JOIN # converted to INNER JOIN with first constant inner table # CREATE TABLE t1 ( pk int PRIMARY KEY, i1 int, v1 varchar(1), v2 varchar(1), KEY v1 (v1,i1) ) engine=MyISAM; INSERT INTO t1 VALUES (8,3,'c','c'),(9,4,'z','z'),(10,3,'i','i'),(11,186,'x','x'), (14,226,'m','m'),(15,133,'p','p'); CREATE TABLE t2 ( pk int PRIMARY KEY, i1 int, v1 varchar(1), v2 varchar(1) ) engine=MyISAM; INSERT INTO t2 VALUES (10,6,'p','p'); EXPLAIN EXTENDED SELECT STRAIGHT_JOIN t2.v2 FROM (t1 as tb1 LEFT JOIN t1 AS tb2 ON tb2.v1 = tb1.v2) RIGHT JOIN (t2,t1) ON t1.pk = t2.pk AND t2.v2 = tb1.v1 WHERE tb1.pk = 40 ORDER BY tb1.i1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables Warnings: Note 1003 select straight_join 'p' AS `v2` from `test`.`t1` join `test`.`t1` `tb1` left join `test`.`t1` `tb2` on(multiple equal(NULL, NULL)) where 0 order by NULL EXPLAIN EXTENDED SELECT STRAIGHT_JOIN t2.v2 FROM (t2,t1) LEFT JOIN (t1 as tb1 LEFT JOIN t1 AS tb2 ON tb2.v1 = tb1.v2) ON t1.pk = t2.pk AND t2.v2 = tb1.v1 WHERE tb1.pk = 40 ORDER BY tb1.i1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables Warnings: Note 1003 select straight_join 'p' AS `v2` from `test`.`t1` join `test`.`t1` `tb1` left join `test`.`t1` `tb2` on(multiple equal(NULL, NULL)) where 0 order by NULL SELECT STRAIGHT_JOIN DISTINCT t2.v2 FROM (t1 as tb1 LEFT JOIN t1 AS tb2 ON tb2.v1 = tb1.v2) RIGHT JOIN (t2,t1) ON t1.pk = t2.pk AND t2.v2 = tb1.v1 WHERE tb1.pk = 40 ORDER BY tb1.i1; v2 DROP TABLE t1,t2; # end of 5.5 tests SET optimizer_switch=@save_optimizer_switch; set join_cache_level=default; show variables like 'join_cache_level'; Variable_name Value join_cache_level 2 set @@optimizer_switch=@save_optimizer_switch_jcl6; set @optimizer_switch_for_join_outer_test=NULL; set @join_cache_level_for_join_outer_test=NULL;