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drop table if exists t1,t2,t3;
CREATE TABLE t1 (id int,facility char(20));
CREATE TABLE t2 (facility char(20));
INSERT INTO t1 VALUES (NULL,NULL);
INSERT INTO t1 VALUES (-1,'');
INSERT INTO t1 VALUES (0,'');
INSERT INTO t1 VALUES (1,'/L');
INSERT INTO t1 VALUES (2,'A01');
INSERT INTO t1 VALUES (3,'ANC');
INSERT INTO t1 VALUES (4,'F01');
INSERT INTO t1 VALUES (5,'FBX');
INSERT INTO t1 VALUES (6,'MT');
INSERT INTO t1 VALUES (7,'P');
INSERT INTO t1 VALUES (8,'RV');
INSERT INTO t1 VALUES (9,'SRV');
INSERT INTO t1 VALUES (10,'VMT');
INSERT INTO t2 SELECT DISTINCT FACILITY FROM t1;
select id from t1 group by id;
id
NULL
-1
0
1
2
3
4
5
6
7
8
9
10
select * from t1 order by id;
id facility
NULL NULL
-1
0
1 /L
2 A01
3 ANC
4 F01
5 FBX
6 MT
7 P
8 RV
9 SRV
10 VMT
select id-5,facility from t1 order by "id-5";
id-5 facility
NULL NULL
-6
-5
-4 /L
-3 A01
-2 ANC
-1 F01
0 FBX
1 MT
2 P
3 RV
4 SRV
5 VMT
select id,concat(facility) from t1 group by id ;
id concat(facility)
NULL NULL
-1
0
1 /L
2 A01
3 ANC
4 F01
5 FBX
6 MT
7 P
8 RV
9 SRV
10 VMT
select id+0 as a,max(id),concat(facility) as b from t1 group by a order by b desc,a;
a max(id) b
NULL NULL NULL
10 10 VMT
9 9 SRV
8 8 RV
7 7 P
6 6 MT
5 5 FBX
4 4 F01
3 3 ANC
2 2 A01
1 1 /L
-1 -1
0 0
select id >= 0 and id <= 5 as grp,count(*) from t1 group by grp;
grp count(*)
NULL 1
0 6
1 6
SELECT DISTINCT FACILITY FROM t1;
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
SELECT FACILITY FROM t2;
FACILITY
NULL
/L
A01
ANC
F01
FBX
MT
P
RV
SRV
VMT
SELECT count(*) from t1,t2 where t1.facility=t2.facility;
count(*)
12
select count(facility) from t1;
count(facility)
12
select count(*) from t1;
count(*)
13
select count(*) from t1 where facility IS NULL;
count(*)
1
select count(*) from t1 where facility = NULL;
count(*)
0
select count(*) from t1 where facility IS NOT NULL;
count(*)
12
select count(*) from t1 where id IS NULL;
count(*)
1
select count(*) from t1 where id IS NOT NULL;
count(*)
12
drop table t1,t2;
CREATE TABLE t1 (UserId int(11) DEFAULT '0' NOT NULL);
INSERT INTO t1 VALUES (20);
INSERT INTO t1 VALUES (27);
SELECT UserId FROM t1 WHERE Userid=22;
UserId
SELECT UserId FROM t1 WHERE UserId=22 group by Userid;
UserId
SELECT DISTINCT UserId FROM t1 WHERE UserId=22 group by Userid;
UserId
SELECT DISTINCT UserId FROM t1 WHERE UserId=22;
UserId
drop table t1;
CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
INSERT INTO t1 VALUES (1,1),(2,1);
CREATE TABLE t2 (a int(10) unsigned not null, key (A));
INSERT INTO t2 VALUES (1),(2);
CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
INSERT INTO t3 VALUES (1,'1'),(2,'2');
SELECT DISTINCT t3.b FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
b
1
INSERT INTO t2 values (1),(2),(3);
INSERT INTO t3 VALUES (1,'1'),(2,'2'),(1,'1'),(2,'2');
explain SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index a a 5 NULL 6 Using index; Using temporary
1 SIMPLE t2 index a a 4 NULL 5 Using index; Distinct
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 t2.a 1 Using where; Distinct
SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
a
1
create temporary table t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
insert into t4 select * from t3;
insert into t3 select * from t4;
explain select distinct t1.a from t1,t3 where t1.a=t3.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index PRIMARY PRIMARY 4 NULL 2 Using index; Using temporary
1 SIMPLE t3 ref a a 5 t1.a 10 Using where; Using index; Distinct
select distinct t1.a from t1,t3 where t1.a=t3.a;
a
1
2
select distinct 1 from t1,t3 where t1.a=t3.a;
1
1
explain SELECT distinct t1.a from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 2 Using index
explain SELECT distinct t1.a from t1 order by a desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 2 Using index
explain SELECT t1.a from t1 group by a order by a desc;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 2 Using index
explain SELECT distinct t1.a from t1 order by a desc limit 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 2 Using index
explain SELECT distinct a from t3 order by a desc limit 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index NULL a 5 NULL 204 Using index
explain SELECT distinct a,b from t3 order by a+1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 204 Using temporary; Using filesort
explain SELECT distinct a,b from t3 order by a limit 10;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index NULL a 5 NULL 204 Using temporary
explain SELECT a,b from t3 group by a,b order by a+1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 204 Using temporary; Using filesort
drop table t1,t2,t3,t4;
CREATE TABLE t1 (name varchar(255));
INSERT INTO t1 VALUES ('aa'),('ab'),('ac'),('ad'),('ae');
SELECT DISTINCT * FROM t1 LIMIT 2;
name
aa
ab
SELECT DISTINCT name FROM t1 LIMIT 2;
name
aa
ab
SELECT DISTINCT 1 FROM t1 LIMIT 2;
1
1
drop table t1;
CREATE TABLE t1 (
ID int(11) NOT NULL auto_increment,
NAME varchar(75) DEFAULT '' NOT NULL,
LINK_ID int(11) DEFAULT '0' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME),
KEY LINK_ID (LINK_ID)
);
INSERT INTO t1 (ID, NAME, LINK_ID) VALUES (1,'Mike',0),(2,'Jack',0),(3,'Bill',0);
CREATE TABLE t2 (
ID int(11) NOT NULL auto_increment,
NAME varchar(150) DEFAULT '' NOT NULL,
PRIMARY KEY (ID),
KEY NAME (NAME)
);
SELECT DISTINCT
t2.id AS key_link_id,
t2.name AS link
FROM t1
LEFT JOIN t2 ON t1.link_id=t2.id
GROUP BY t1.id
ORDER BY link;
key_link_id link
NULL NULL
drop table t1,t2;
create table t1 (
id int not null,
name tinytext not null,
unique (id)
);
create table t2 (
id int not null,
idx int not null,
unique (id, idx)
);
create table t3 (
id int not null,
idx int not null,
unique (id, idx)
);
insert into t1 values (1,'yes'), (2,'no');
insert into t2 values (1,1);
insert into t3 values (1,1);
EXPLAIN
SELECT DISTINCT
t1.id
from
t1
straight_join
t2
straight_join
t3
straight_join
t1 as j_lj_t2 left join t2 as t2_lj
on j_lj_t2.id=t2_lj.id
straight_join
t1 as j_lj_t3 left join t3 as t3_lj
on j_lj_t3.id=t3_lj.id
WHERE
((t1.id=j_lj_t2.id AND t2_lj.id IS NULL) OR (t1.id=t2.id AND t2.idx=2))
AND ((t1.id=j_lj_t3.id AND t3_lj.id IS NULL) OR (t1.id=t3.id AND t3.idx=2));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index id id 4 NULL 2 Using index; Using temporary
1 SIMPLE t2 index id id 8 NULL 1 Using index; Distinct
1 SIMPLE t3 index id id 8 NULL 1 Using index; Distinct
1 SIMPLE j_lj_t2 index id id 4 NULL 2 Using where; Using index; Distinct
1 SIMPLE t2_lj index id id 8 NULL 1 Using where; Using index; Distinct
1 SIMPLE j_lj_t3 index id id 4 NULL 2 Using where; Using index; Distinct
1 SIMPLE t3_lj index id id 8 NULL 1 Using where; Using index; Distinct
SELECT DISTINCT
t1.id
from
t1
straight_join
t2
straight_join
t3
straight_join
t1 as j_lj_t2 left join t2 as t2_lj
on j_lj_t2.id=t2_lj.id
straight_join
t1 as j_lj_t3 left join t3 as t3_lj
on j_lj_t3.id=t3_lj.id
WHERE
((t1.id=j_lj_t2.id AND t2_lj.id IS NULL) OR (t1.id=t2.id AND t2.idx=2))
AND ((t1.id=j_lj_t3.id AND t3_lj.id IS NULL) OR (t1.id=t3.id AND t3.idx=2));
id
2
drop table t1,t2,t3;
create table t1 (a int not null, b int not null, t time);
insert into t1 values (1,1,"00:06:15"),(1,2,"00:06:15"),(1,2,"00:30:15"),(1,3,"00:06:15"),(1,3,"00:30:15");
select a,sec_to_time(sum(time_to_sec(t))) from t1 group by a,b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
1 00:36:30
select distinct a,sec_to_time(sum(time_to_sec(t))) from t1 group by a,b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
create table t2 (a int not null primary key, b int);
insert into t2 values (1,1),(2,2),(3,3);
select t1.a,sec_to_time(sum(time_to_sec(t))) from t1 left join t2 on (t1.b=t2.a) group by t1.a,t2.b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
1 00:36:30
select distinct t1.a,sec_to_time(sum(time_to_sec(t))) from t1 left join t2 on (t1.b=t2.a) group by t1.a,t2.b;
a sec_to_time(sum(time_to_sec(t)))
1 00:06:15
1 00:36:30
drop table t1,t2;
create table t1 (a int not null,b char(5), c text);
insert into t1 (a) values (1),(2),(3),(4),(1),(2),(3),(4);
select distinct a from t1 group by b,a having a > 2 order by a desc;
a
4
3
select distinct a,c from t1 group by b,c,a having a > 2 order by a desc;
a c
4 NULL
3 NULL
drop table t1;
create table t1 (a char(1), key(a)) type=myisam;
insert into t1 values('1'),('1');
select * from t1 where a >= '1';
a
1
1
select distinct a from t1 order by a desc;
a
1
select distinct a from t1 where a >= '1' order by a desc;
a
1
drop table t1;
CREATE TABLE t1 (email varchar(50), infoID BIGINT, dateentered DATETIME);
CREATE TABLE t2 (infoID BIGINT, shipcode varchar(10));
INSERT INTO t1 (email, infoID, dateentered) VALUES
('test1@testdomain.com', 1, '2002-07-30 22:56:38'),
('test1@testdomain.com', 1, '2002-07-27 22:58:16'),
('test2@testdomain.com', 1, '2002-06-19 15:22:19'),
('test2@testdomain.com', 2, '2002-06-18 14:23:47'),
('test3@testdomain.com', 1, '2002-05-19 22:17:32');
INSERT INTO t2(infoID, shipcode) VALUES
(1, 'Z001'),
(2, 'R002');
SELECT DISTINCTROW email, shipcode FROM t1, t2 WHERE t1.infoID=t2.infoID;
email shipcode
test1@testdomain.com Z001
test2@testdomain.com Z001
test3@testdomain.com Z001
test2@testdomain.com R002
SELECT DISTINCTROW email FROM t1 ORDER BY dateentered DESC;
email
test1@testdomain.com
test2@testdomain.com
test3@testdomain.com
SELECT DISTINCTROW email, shipcode FROM t1, t2 WHERE t1.infoID=t2.infoID ORDER BY dateentered DESC;
email shipcode
test1@testdomain.com Z001
test2@testdomain.com Z001
test2@testdomain.com R002
test3@testdomain.com Z001
drop table t1,t2;
CREATE TABLE t1 (privatemessageid int(10) unsigned NOT NULL auto_increment, folderid smallint(6) NOT NULL default '0', userid int(10) unsigned NOT NULL default '0', touserid int(10) unsigned NOT NULL default '0', fromuserid int(10) unsigned NOT NULL default '0', title varchar(250) NOT NULL default '', message mediumtext NOT NULL, dateline int(10) unsigned NOT NULL default '0', showsignature smallint(6) NOT NULL default '0', iconid smallint(5) unsigned NOT NULL default '0', messageread smallint(6) NOT NULL default '0', readtime int(10) unsigned NOT NULL default '0', receipt smallint(6) unsigned NOT NULL default '0', deleteprompt smallint(6) unsigned NOT NULL default '0', multiplerecipients smallint(6) unsigned NOT NULL default '0', PRIMARY KEY (privatemessageid), KEY userid (userid)) TYPE=MyISAM;
INSERT INTO t1 VALUES (128,0,33,33,8,':D','',996121863,1,0,2,996122850,2,0,0);
CREATE TABLE t2 (userid int(10) unsigned NOT NULL auto_increment, usergroupid smallint(5) unsigned NOT NULL default '0', username varchar(50) NOT NULL default '', password varchar(50) NOT NULL default '', email varchar(50) NOT NULL default '', styleid smallint(5) unsigned NOT NULL default '0', parentemail varchar(50) NOT NULL default '', coppauser smallint(6) NOT NULL default '0', homepage varchar(100) NOT NULL default '', icq varchar(20) NOT NULL default '', aim varchar(20) NOT NULL default '', yahoo varchar(20) NOT NULL default '', signature mediumtext NOT NULL, adminemail smallint(6) NOT NULL default '0', showemail smallint(6) NOT NULL default '0', invisible smallint(6) NOT NULL default '0', usertitle varchar(250) NOT NULL default '', customtitle smallint(6) NOT NULL default '0', joindate int(10) unsigned NOT NULL default '0', cookieuser smallint(6) NOT NULL default '0', daysprune smallint(6) NOT NULL default '0', lastvisit int(10) unsigned NOT NULL default '0', lastactivity int(10) unsigned NOT NULL default '0', lastpost int(10) unsigned NOT NULL default '0', posts smallint(5) unsigned NOT NULL default '0', timezoneoffset varchar(4) NOT NULL default '', emailnotification smallint(6) NOT NULL default '0', buddylist mediumtext NOT NULL, ignorelist mediumtext NOT NULL, pmfolders mediumtext NOT NULL, receivepm smallint(6) NOT NULL default '0', emailonpm smallint(6) NOT NULL default '0', pmpopup smallint(6) NOT NULL default '0', avatarid smallint(6) NOT NULL default '0', avatarrevision int(6) unsigned NOT NULL default '0', options smallint(6) NOT NULL default '15', birthday date NOT NULL default '0000-00-00', maxposts smallint(6) NOT NULL default '-1', startofweek smallint(6) NOT NULL default '1', ipaddress varchar(20) NOT NULL default '', referrerid int(10) unsigned NOT NULL default '0', nosessionhash smallint(6) NOT NULL default '0', autorefresh smallint(6) NOT NULL default '-1', messagepopup tinyint(2) NOT NULL default '0', inforum smallint(5) unsigned NOT NULL default '0', ratenum smallint(5) unsigned NOT NULL default '0', ratetotal smallint(5) unsigned NOT NULL default '0', allowrate smallint(5) unsigned NOT NULL default '1', PRIMARY KEY (userid), KEY usergroupid (usergroupid), KEY username (username), KEY inforum (inforum)) TYPE=MyISAM;
INSERT INTO t2 VALUES (33,6,'Kevin','0','kevin@stileproject.com',1,'',0,'http://www.stileproject.com','','','','',1,1,0,'Administrator',0,996120694,1,-1,1030996168,1031027028,1030599436,36,'-6',0,'','','',1,0,1,0,0,15,'0000-00-00',-1,1,'64.0.0.0',0,1,-1,0,0,4,19,1);
SELECT DISTINCT t1.*, t2.* FROM t1 LEFT JOIN t2 ON (t2.userid = t1.touserid);
privatemessageid folderid userid touserid fromuserid title message dateline showsignature iconid messageread readtime receipt deleteprompt multiplerecipients userid usergroupid username password email styleid parentemail coppauser homepage icq aim yahoo signature adminemail showemail invisible usertitle customtitle joindate cookieuser daysprune lastvisit lastactivity lastpost posts timezoneoffset emailnotification buddylist ignorelist pmfolders receivepm emailonpm pmpopup avatarid avatarrevision options birthday maxposts startofweek ipaddress referrerid nosessionhash autorefresh messagepopup inforum ratenum ratetotal allowrate
128 0 33 33 8 :D 996121863 1 0 2 996122850 2 0 0 33 6 Kevin 0 kevin@stileproject.com 1 0 http://www.stileproject.com 1 1 0 Administrator 0 996120694 1 -1 1030996168 1031027028 1030599436 36 -6 0 1 0 1 0 0 15 0000-00-00 -1 1 64.0.0.0 0 1 -1 0 0 4 19 1
DROP TABLE t1,t2;
CREATE TABLE t1 (a int primary key, b int, c int);
INSERT t1 VALUES (1,2,3);
CREATE TABLE t2 (a int primary key, b int, c int);
INSERT t2 VALUES (3,4,5);
SELECT DISTINCT t1.a, t2.b FROM t1, t2 WHERE t1.a=1 ORDER BY t2.c;
a b
1 4
DROP TABLE t1,t2;
|