drop table if exists t1,t2,t3;
CREATE TABLE t1 (
spID int(10) unsigned,
userID int(10) unsigned,
score smallint(5) unsigned,
lsg char(40),
date date
);
INSERT INTO t1 VALUES (1,1,1,'','0000-00-00');
INSERT INTO t1 VALUES (2,2,2,'','0000-00-00');
INSERT INTO t1 VALUES (2,1,1,'','0000-00-00');
INSERT INTO t1 VALUES (3,3,3,'','0000-00-00');
CREATE TABLE t2 (
userID int(10) unsigned DEFAULT '0' NOT NULL auto_increment,
niName char(15),
passwd char(8),
mail char(50),
isAukt enum('N','Y') DEFAULT 'N',
vName char(30),
nName char(40),
adr char(60),
plz char(5),
ort char(35),
land char(20),
PRIMARY KEY (userID)
);
INSERT INTO t2 VALUES (1,'name','pass','mail','Y','v','n','adr','1','1','1');
INSERT INTO t2 VALUES (2,'name','pass','mail','Y','v','n','adr','1','1','1');
INSERT INTO t2 VALUES (3,'name','pass','mail','Y','v','n','adr','1','1','1');
SELECT t2.userid, MIN(t1.score) FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY t2.userid;
userid	MIN(t1.score)
1	1
2	2
3	3
SELECT t2.userid, MIN(t1.score) FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY t2.userid ORDER BY NULL;
userid	MIN(t1.score)
1	1
2	2
3	3
SELECT t2.userid, MIN(t1.score) FROM t1, t2 WHERE t1.userID=t2.userID AND t1.spID=2  GROUP BY t2.userid;
userid	MIN(t1.score)
1	1
2	2
SELECT t2.userid, MIN(t1.score+0.0) FROM t1, t2 WHERE t1.userID=t2.userID AND t1.spID=2  GROUP BY t2.userid;
userid	MIN(t1.score+0.0)
1	1.0
2	2.0
SELECT t2.userid, MIN(t1.score+0.0) FROM t1, t2 WHERE t1.userID=t2.userID AND t1.spID=2  GROUP BY t2.userid ORDER BY NULL;
userid	MIN(t1.score+0.0)
1	1.0
2	2.0
drop table test.t1,test.t2;
CREATE TABLE t1 (
PID int(10) unsigned DEFAULT '0' NOT NULL auto_increment,
payDate date DEFAULT '0000-00-00' NOT NULL,
recDate datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
URID int(10) unsigned DEFAULT '0' NOT NULL,
CRID int(10) unsigned DEFAULT '0' NOT NULL,
amount int(10) unsigned DEFAULT '0' NOT NULL,
operator int(10) unsigned,
method enum('unknown','cash','dealer','check','card','lazy','delayed','test') DEFAULT 'unknown' NOT NULL,
DIID int(10) unsigned,
reason char(1) binary DEFAULT '' NOT NULL,
code_id int(10) unsigned,
qty mediumint(8) unsigned DEFAULT '0' NOT NULL,
PRIMARY KEY (PID),
KEY URID (URID),
KEY reason (reason),
KEY method (method),
KEY payDate (payDate)
);
INSERT INTO t1 VALUES (1,'1970-01-01','1997-10-17 00:00:00',2529,1,21000,11886,'check',0,'F',16200,6);
SELECT COUNT(P.URID),SUM(P.amount),P.method, MIN(PP.recdate+0) > 19980501000000   AS IsNew FROM t1 AS P JOIN t1 as PP WHERE P.URID = PP.URID GROUP BY method,IsNew;
Can't group on 'IsNew'
drop table t1;
CREATE TABLE t1 (
cid mediumint(9) DEFAULT '0' NOT NULL auto_increment,
firstname varchar(32) DEFAULT '' NOT NULL,
surname varchar(32) DEFAULT '' NOT NULL,
PRIMARY KEY (cid)
);
INSERT INTO t1 VALUES (1,'That','Guy');
INSERT INTO t1 VALUES (2,'Another','Gent');
CREATE TABLE t2 (
call_id mediumint(8) DEFAULT '0' NOT NULL auto_increment,
contact_id mediumint(8) DEFAULT '0' NOT NULL,
PRIMARY KEY (call_id),
KEY contact_id (contact_id)
);
lock tables t1 read,t2 write;
INSERT INTO t2 VALUES (10,2);
INSERT INTO t2 VALUES (18,2);
INSERT INTO t2 VALUES (62,2);
INSERT INTO t2 VALUES (91,2);
INSERT INTO t2 VALUES (92,2);
SELECT cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid;
cid	CONCAT(firstname, ' ', surname)	COUNT(call_id)
SELECT cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid ORDER BY NULL;
cid	CONCAT(firstname, ' ', surname)	COUNT(call_id)
SELECT HIGH_PRIORITY cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid ORDER BY surname, firstname;
cid	CONCAT(firstname, ' ', surname)	COUNT(call_id)
drop table t1,t2;
unlock tables;
CREATE TABLE t1 (
bug_id mediumint(9) DEFAULT '0' NOT NULL auto_increment,
groupset bigint(20) DEFAULT '0' NOT NULL,
assigned_to mediumint(9) DEFAULT '0' NOT NULL,
bug_file_loc text,
bug_severity enum('blocker','critical','major','normal','minor','trivial','enhancement') DEFAULT 'blocker' NOT NULL,
bug_status enum('NEW','ASSIGNED','REOPENED','RESOLVED','VERIFIED','CLOSED') DEFAULT 'NEW' NOT NULL,
creation_ts datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
delta_ts timestamp(14),
short_desc mediumtext,
long_desc mediumtext,
op_sys enum('All','Windows 3.1','Windows 95','Windows 98','Windows NT','Windows 2000','Linux','other') DEFAULT 'All' NOT NULL,
priority enum('P1','P2','P3','P4','P5') DEFAULT 'P1' NOT NULL,
product varchar(64) DEFAULT '' NOT NULL,
rep_platform enum('All','PC','VTD-8','Other'),
reporter mediumint(9) DEFAULT '0' NOT NULL,
version varchar(16) DEFAULT '' NOT NULL,
component varchar(50) DEFAULT '' NOT NULL,
resolution enum('','FIXED','INVALID','WONTFIX','LATER','REMIND','DUPLICATE','WORKSFORME') DEFAULT '' NOT NULL,
target_milestone varchar(20) DEFAULT '' NOT NULL,
qa_contact mediumint(9) DEFAULT '0' NOT NULL,
status_whiteboard mediumtext NOT NULL,
votes mediumint(9) DEFAULT '0' NOT NULL,
PRIMARY KEY (bug_id),
KEY assigned_to (assigned_to),
KEY creation_ts (creation_ts),
KEY delta_ts (delta_ts),
KEY bug_severity (bug_severity),
KEY bug_status (bug_status),
KEY op_sys (op_sys),
KEY priority (priority),
KEY product (product),
KEY reporter (reporter),
KEY version (version),
KEY component (component),
KEY resolution (resolution),
KEY target_milestone (target_milestone),
KEY qa_contact (qa_contact),
KEY votes (votes)
);
INSERT INTO t1 VALUES (1,0,0,'','normal','','2000-02-10 09:25:12',20000321114747,'','','Linux','P1','TestProduct','PC',3,'other','TestComponent','','M1',0,'',0);
INSERT INTO t1 VALUES (9,0,0,'','enhancement','','2000-03-10 11:49:36',20000321114747,'','','All','P5','AAAAA','PC',3,'2.00 CD - Pre','BBBBBBBBBBBBB - conversion','','',0,'',0);
INSERT INTO t1 VALUES (10,0,0,'','enhancement','','2000-03-10 18:10:16',20000321114747,'','','All','P4','AAAAA','PC',3,'2.00 CD - Pre','BBBBBBBBBBBBB - conversion','','',0,'',0);
INSERT INTO t1 VALUES (7,0,0,'','critical','','2000-03-09 10:50:21',20000321114747,'','','All','P1','AAAAA','PC',3,'2.00 CD - Pre','BBBBBBBBBBBBB - generic','','',0,'',0);
INSERT INTO t1 VALUES (6,0,0,'','normal','','2000-03-09 10:42:44',20000321114747,'','','All','P2','AAAAA','PC',3,'2.00 CD - Pre','kkkkkkkkkkk lllllllllll','','',0,'',0);
INSERT INTO t1 VALUES (8,0,0,'','major','','2000-03-09 11:32:14',20000321114747,'','','All','P3','AAAAA','PC',3,'2.00 CD - Pre','kkkkkkkkkkk lllllllllll','','',0,'',0);
INSERT INTO t1 VALUES (5,0,0,'','enhancement','','2000-03-09 10:38:59',20000321114747,'','','All','P5','CCC/CCCCCC','PC',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (4,0,0,'','normal','','2000-03-08 18:32:14',20000321114747,'','','other','P2','TestProduct','Other',3,'other','TestComponent2','','',0,'',0);
INSERT INTO t1 VALUES (3,0,0,'','normal','','2000-03-08 18:30:52',20000321114747,'','','other','P2','TestProduct','Other',3,'other','TestComponent','','',0,'',0);
INSERT INTO t1 VALUES (2,0,0,'','enhancement','','2000-03-08 18:24:51',20000321114747,'','','All','P2','TestProduct','Other',4,'other','TestComponent2','','',0,'',0);
INSERT INTO t1 VALUES (11,0,0,'','blocker','','2000-03-13 09:43:41',20000321114747,'','','All','P2','CCC/CCCCCC','PC',5,'7.00','DDDDDDDDD','','',0,'',0);
INSERT INTO t1 VALUES (12,0,0,'','normal','','2000-03-13 16:14:31',20000321114747,'','','All','P2','AAAAA','PC',3,'2.00 CD - Pre','kkkkkkkkkkk lllllllllll','','',0,'',0);
INSERT INTO t1 VALUES (13,0,0,'','normal','','2000-03-15 16:20:44',20000321114747,'','','other','P2','TestProduct','Other',3,'other','TestComponent','','',0,'',0);
INSERT INTO t1 VALUES (14,0,0,'','blocker','','2000-03-15 18:13:47',20000321114747,'','','All','P1','AAAAA','PC',3,'2.00 CD - Pre','BBBBBBBBBBBBB - generic','','',0,'',0);
INSERT INTO t1 VALUES (15,0,0,'','minor','','2000-03-16 18:03:28',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','DDDDDDDDD','','',0,'',0);
INSERT INTO t1 VALUES (16,0,0,'','normal','','2000-03-16 18:33:41',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (17,0,0,'','normal','','2000-03-16 18:34:18',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (18,0,0,'','normal','','2000-03-16 18:34:56',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (19,0,0,'','enhancement','','2000-03-16 18:35:34',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (20,0,0,'','enhancement','','2000-03-16 18:36:23',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (21,0,0,'','enhancement','','2000-03-16 18:37:23',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (22,0,0,'','enhancement','','2000-03-16 18:38:16',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','Administration','','',0,'',0);
INSERT INTO t1 VALUES (23,0,0,'','normal','','2000-03-16 18:58:12',20000321114747,'','','All','P2','CCC/CCCCCC','Other',5,'7.00','DDDDDDDDD','','',0,'',0);
INSERT INTO t1 VALUES (24,0,0,'','normal','','2000-03-17 11:08:10',20000321114747,'','','All','P2','AAAAAAAA-AAA','PC',3,'2.8','Web Interface','','',0,'',0);
INSERT INTO t1 VALUES (25,0,0,'','normal','','2000-03-17 11:10:45',20000321114747,'','','All','P2','AAAAAAAA-AAA','PC',3,'2.8','Web Interface','','',0,'',0);
INSERT INTO t1 VALUES (26,0,0,'','normal','','2000-03-17 11:15:47',20000321114747,'','','All','P2','AAAAAAAA-AAA','PC',3,'2.8','Web Interface','','',0,'',0);
INSERT INTO t1 VALUES (27,0,0,'','normal','','2000-03-17 17:45:41',20000321114747,'','','All','P2','CCC/CCCCCC','PC',5,'7.00','DDDDDDDDD','','',0,'',0);
INSERT INTO t1 VALUES (28,0,0,'','normal','','2000-03-20 09:51:45',20000321114747,'','','Windows NT','P2','TestProduct','PC',8,'other','TestComponent','','',0,'',0);
INSERT INTO t1 VALUES (29,0,0,'','normal','','2000-03-20 11:15:09',20000321114747,'','','All','P5','AAAAAAAA-AAA','PC',3,'2.8','Web Interface','','',0,'',0);
CREATE TABLE t2 (
value tinytext,
program varchar(64),
initialowner tinytext NOT NULL,
initialqacontact tinytext NOT NULL,
description mediumtext NOT NULL
);
INSERT INTO t2 VALUES ('TestComponent','TestProduct','id0001','','');
INSERT INTO t2 VALUES ('BBBBBBBBBBBBB - conversion','AAAAA','id0001','','');
INSERT INTO t2 VALUES ('BBBBBBBBBBBBB - generic','AAAAA','id0001','','');
INSERT INTO t2 VALUES ('TestComponent2','TestProduct','id0001','','');
INSERT INTO t2 VALUES ('BBBBBBBBBBBBB - eeeeeeeee','AAAAA','id0001','','');
INSERT INTO t2 VALUES ('kkkkkkkkkkk lllllllllll','AAAAA','id0001','','');
INSERT INTO t2 VALUES ('Test Procedures','AAAAA','id0001','','');
INSERT INTO t2 VALUES ('Documentation','AAAAA','id0003','','');
INSERT INTO t2 VALUES ('DDDDDDDDD','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Eeeeeeee Lite','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Eeeeeeee Full','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Administration','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Distribution','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Setup','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Unspecified','CCC/CCCCCC','id0002','','');
INSERT INTO t2 VALUES ('Web Interface','AAAAAAAA-AAA','id0001','','');
INSERT INTO t2 VALUES ('Host communication','AAAAA','id0001','','');
select value,description,bug_id from t2 left join t1 on t2.program=t1.product and t2.value=t1.component where program="AAAAA";
value	description	bug_id
BBBBBBBBBBBBB - conversion		9
BBBBBBBBBBBBB - conversion		10
BBBBBBBBBBBBB - generic		7
BBBBBBBBBBBBB - generic		14
BBBBBBBBBBBBB - eeeeeeeee		NULL
kkkkkkkkkkk lllllllllll		6
kkkkkkkkkkk lllllllllll		8
kkkkkkkkkkk lllllllllll		12
Test Procedures		NULL
Documentation		NULL
Host communication		NULL
select value,description,COUNT(bug_id) from t2 left join t1 on t2.program=t1.product and t2.value=t1.component where program="AAAAA" group by value;
value	description	COUNT(bug_id)
BBBBBBBBBBBBB - conversion		2
BBBBBBBBBBBBB - eeeeeeeee		0
BBBBBBBBBBBBB - generic		2
Documentation		0
Host communication		0
kkkkkkkkkkk lllllllllll		3
Test Procedures		0
select value,description,COUNT(bug_id) from t2 left join t1 on t2.program=t1.product and t2.value=t1.component where program="AAAAA" group by value having COUNT(bug_id) IN (0,2);
value	description	COUNT(bug_id)
BBBBBBBBBBBBB - conversion		2
BBBBBBBBBBBBB - eeeeeeeee		0
BBBBBBBBBBBBB - generic		2
Documentation		0
Host communication		0
Test Procedures		0
drop table t1,t2;
create table t1 (foo int);
insert into t1 values (1);
select 1+1, "a",count(*) from t1 where foo in (2);
1+1	a	count(*)
2	a	0
insert into t1 values (1);
select 1+1,"a",count(*) from t1 where foo in (2);
1+1	a	count(*)
2	a	0
drop table t1;
CREATE TABLE t1 (
spID int(10) unsigned,
userID int(10) unsigned,
score smallint(5) unsigned,
key (spid),
key (score)
);
INSERT INTO t1 VALUES (1,1,1),(2,2,2),(2,1,1),(3,3,3),(4,3,3),(5,3,3);
explain select userid,count(*) from t1 group by userid desc;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort
explain select userid,count(*) from t1 group by userid desc order by null;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary
select userid,count(*) from t1 group by userid desc;
userid	count(*)
3	3
2	1
1	2
select userid,count(*) from t1 group by userid desc having (count(*)+1) IN (4,3);
userid	count(*)
3	3
1	2
select userid,count(*) from t1 group by userid desc having 3  IN (1,COUNT(*));
userid	count(*)
3	3
explain select spid,count(*) from t1 where spid between 1 and 2 group by spid desc;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	range	spID	spID	5	NULL	2	Using where; Using index
explain select spid,count(*) from t1 where spid between 1 and 2 group by spid;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	range	spID	spID	5	NULL	2	Using where; Using index
explain select spid,count(*) from t1 where spid between 1 and 2 group by spid order by null;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	range	spID	spID	5	NULL	2	Using where; Using index
select spid,count(*) from t1 where spid between 1 and 2 group by spid;
spid	count(*)
1	1
2	2
select spid,count(*) from t1 where spid between 1 and 2 group by spid desc;
spid	count(*)
2	2
1	1
explain select sql_big_result spid,sum(userid) from t1 group by spid desc;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	Using filesort
explain select sql_big_result spid,sum(userid) from t1 group by spid desc order by null;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	
select sql_big_result spid,sum(userid) from t1 group by spid desc;
spid	sum(userid)
5	3
4	3
3	3
2	3
1	1
explain select sql_big_result score,count(*) from t1 group by score desc;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	index	NULL	score	3	NULL	6	Using index
explain select sql_big_result score,count(*) from t1 group by score desc order by null;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	index	NULL	score	3	NULL	6	Using index
select sql_big_result score,count(*) from t1 group by score desc;
score	count(*)
3	3
2	1
1	2
drop table t1;
CREATE TABLE t1 (a char(1));
INSERT INTO t1 VALUES ('A'),('B'),('A'),('B'),('A'),('B'),(NULL),('a'),('b'),(NULL),('A'),('B'),(NULL);
SELECT a FROM t1 GROUP BY a;
a
NULL
A
B
SELECT a,count(*) FROM t1 GROUP BY a;
a	count(*)
NULL	3
A	5
B	5
SELECT a FROM t1 GROUP BY binary a;
a
NULL
A
B
a
b
SELECT a,count(*) FROM t1 GROUP BY binary a;
a	count(*)
NULL	3
A	4
B	4
a	1
b	1
SELECT binary a FROM t1 GROUP BY 1;
binary a
NULL
A
B
a
b
SELECT binary a,count(*) FROM t1 GROUP BY 1;
binary a	count(*)
NULL	3
A	4
B	4
a	1
b	1
SET SQL_BIG_TABLES=1;
SELECT a FROM t1 GROUP BY a;
a
NULL
A
B
SELECT a,count(*) FROM t1 GROUP BY a;
a	count(*)
NULL	3
A	5
B	5
SELECT a FROM t1 GROUP BY binary a;
a
NULL
A
B
a
b
SELECT a,count(*) FROM t1 GROUP BY binary a;
a	count(*)
NULL	3
A	4
B	4
a	1
b	1
SELECT binary a FROM t1 GROUP BY 1;
binary a
NULL
A
B
a
b
SELECT binary a,count(*) FROM t1 GROUP BY 1;
binary a	count(*)
NULL	3
A	4
B	4
a	1
b	1
SET SQL_BIG_TABLES=0;
drop table t1;
CREATE TABLE t1 (
`a` char(193) default NULL,
`b` char(63) default NULL
);
INSERT INTO t1 VALUES ('abc','def'),('hij','klm');
SELECT CONCAT(a, b) FROM t1 GROUP BY 1;
CONCAT(a, b)
abcdef
hijklm
SELECT CONCAT(a, b),count(*) FROM t1 GROUP BY 1;
CONCAT(a, b)	count(*)
abcdef	1
hijklm	1
SELECT CONCAT(a, b),count(distinct a) FROM t1 GROUP BY 1;
CONCAT(a, b)	count(distinct a)
abcdef	1
hijklm	1
SELECT 1 FROM t1 GROUP BY CONCAT(a, b);
1
1
1
INSERT INTO t1 values ('hij','klm');
SELECT CONCAT(a, b),count(*) FROM t1 GROUP BY 1;
CONCAT(a, b)	count(*)
abcdef	1
hijklm	2
DROP TABLE t1;
drop table if exists t1;
create table t1 (One int unsigned, Two int unsigned, Three int unsigned, Four int unsigned);
insert into t1 values (1,2,1,4),(1,2,2,4),(1,2,3,4),(1,2,4,4),(1,1,1,4),(1,1,2,4),(1,1,3,4),(1,1,4,4),(1,3,1,4),(1,3,2,4),(1,3,3,4),(1,3,4,4);
select One, Two, sum(Four) from t1 group by One,Two;
One	Two	sum(Four)
1	1	16
1	2	16
1	3	16
drop table t1;
create table t1 (id integer primary key not null auto_increment, gender char(1));
insert into t1 values (NULL, 'M'), (NULL, 'F'),(NULL, 'F'),(NULL, 'F'),(NULL, 'M');
create table t2 (user_id integer not null, date date);
insert into t2 values (1, '2002-06-09'),(2, '2002-06-09'),(1, '2002-06-09'),(3, '2002-06-09'),(4, '2002-06-09'),(4, '2002-06-09');
select u.gender as gender, count(distinct  u.id) as dist_count, (count(distinct u.id)/5*100) as percentage from t1 u, t2 l where l.user_id = u.id group by u.gender;
gender	dist_count	percentage
F	3	60.00
M	1	20.00
select u.gender as  gender, count(distinct  u.id) as dist_count, (count(distinct u.id)/5*100) as percentage from t1 u, t2 l where l.user_id = u.id group by u.gender  order by percentage;
gender	dist_count	percentage
M	1	20.00
F	3	60.00
drop table t1,t2;
CREATE TABLE t1 (ID1 int, ID2 int, ID int NOT NULL AUTO_INCREMENT,PRIMARY KEY(ID
));
insert into t1 values (1,244,NULL),(2,243,NULL),(134,223,NULL),(185,186,NULL);
select S.ID as xID, S.ID1 as xID1 from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2;
xID	xID1
1	1
2	2
2	2
3	134
3	134
3	134
4	185
4	185
4	185
4	185
select S.ID as xID, S.ID1 as xID1, repeat('*',count(distinct yS.ID)) as Level from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2 group by xID order by xID1;
xID	xID1	Level
1	1	*
2	2	**
3	134	***
4	185	****
drop table t1;
CREATE TABLE t1 (
pid int(11) unsigned NOT NULL default '0',
c1id int(11) unsigned default NULL,
c2id int(11) unsigned default NULL,
value int(11) unsigned NOT NULL default '0',
UNIQUE KEY pid2 (pid,c1id,c2id),
UNIQUE KEY pid (pid,value)
) TYPE=MyISAM;
INSERT INTO t1 VALUES (1, 1, NULL, 1),(1, 2, NULL, 2),(1, NULL, 3, 3),(1, 4, NULL, 4),(1, 5, NULL, 5);
CREATE TABLE t2 (
id int(11) unsigned NOT NULL default '0',
active enum('Yes','No') NOT NULL default 'Yes',
PRIMARY KEY  (id)
) TYPE=MyISAM;
INSERT INTO t2 VALUES (1, 'Yes'),(2, 'No'),(4, 'Yes'),(5, 'No');
CREATE TABLE t3 (
id int(11) unsigned NOT NULL default '0',
active enum('Yes','No') NOT NULL default 'Yes',
PRIMARY KEY  (id)
);
INSERT INTO t3 VALUES (3, 'Yes');
select * from t1 AS m LEFT JOIN t2 AS c1 ON m.c1id = 
c1.id AND c1.active = 'Yes' LEFT JOIN t3 AS c2 ON m.c2id = c2.id AND 
c2.active = 'Yes' WHERE m.pid=1  AND (c1.id IS NOT NULL OR c2.id IS NOT NULL);
pid	c1id	c2id	value	id	active	id	active
1	1	NULL	1	1	Yes	NULL	NULL
1	NULL	3	3	NULL	NULL	3	Yes
1	4	NULL	4	4	Yes	NULL	NULL
select max(value) from t1 AS m LEFT JOIN t2 AS c1 ON 
m.c1id = c1.id AND c1.active = 'Yes' LEFT JOIN t3 AS c2 ON m.c2id = 
c2.id AND c2.active = 'Yes' WHERE m.pid=1  AND (c1.id IS NOT NULL OR c2.id IS 
NOT NULL);
max(value)
4
drop table t1,t2,t3;
create table t1 (a blob null);
insert into t1 values (NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(""),(""),(""),("b");
select a,count(*) from t1 group by a;
a	count(*)
NULL	9
	3
b	1
set option sql_big_tables=1;
select a,count(*) from t1 group by a;
a	count(*)
NULL	9
	3
b	1
drop table t1;
create table t1 (a int not null, b int not null);
insert into t1 values (1,1),(1,2),(3,1),(3,2),(2,2),(2,1);
create table t2 (a int not null, b int not null, key(a));
insert into t2 values (1,3),(3,1),(2,2),(1,1);
select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
a	b
1	1
1	3
2	2
3	1
select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
a	b
1	3
3	1
2	2
1	1
explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort
t2	ALL	a	NULL	NULL	NULL	4	Using where
explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
table	type	possible_keys	key	key_len	ref	rows	Extra
t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary
t2	ALL	a	NULL	NULL	NULL	4	Using where
drop table t1,t2;
a	MAX(b)	INTERVAL (MAX(b), 1,3,10,30,39,40,50,60,100,1000)
1	4	2
10	43	6
a	MAX(b)	CASE MAX(b) when 4 then 4 when 43 then 43 else 0 end
1	4	4
10	43	43
a	MAX(b)	FIELD(MAX(b), '43', '4', '5')
1	4	2
10	43	1
a	MAX(b)	CONCAT_WS(MAX(b), '43', '4', '5')
1	4	434445
10	43	43434435
a	MAX(b)	ELT(MAX(b), 'a', 'b', 'c', 'd', 'e', 'f')
1	4	d
10	43	NULL
a	MAX(b)	MAKE_SET(MAX(b), 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h')
1	4	c
10	43	a,b,d,f