drop table if exists t1, t2;
create table t1 (grp int, a bigint unsigned, c char(10) not null, d char(10) not null);
insert into t1 values (1,1,"a","a");
insert into t1 values (2,2,"b","a");
insert into t1 values (2,3,"c","b");
insert into t1 values (3,4,"E","a");
insert into t1 values (3,5,"C","b");
insert into t1 values (3,6,"D","b");
insert into t1 values (3,7,"d","d");
insert into t1 values (3,8,"d","d");
insert into t1 values (3,9,"D","c");
select grp,group_concat(c) from t1 group by grp;
grp	group_concat(c)
1	a
2	b,c
3	E,C,D,d,d,D
explain extended select grp,group_concat(c) from t1 group by grp;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	100.00	Using filesort
Warnings:
Note	1003	select `test`.`t1`.`grp` AS `grp`,group_concat(`test`.`t1`.`c` separator ',') AS `group_concat(c)` from `test`.`t1` group by `test`.`t1`.`grp`
select grp,group_concat(a,c) from t1 group by grp;
grp	group_concat(a,c)
1	1a
2	2b,3c
3	4E,5C,6D,7d,8d,9D
select grp,group_concat("(",a,":",c,")") from t1 group by grp;
grp	group_concat("(",a,":",c,")")
1	(1:a)
2	(2:b),(3:c)
3	(4:E),(5:C),(6:D),(7:d),(8:d),(9:D)
select grp,group_concat(c separator ",") from t1 group by grp;
grp	group_concat(c separator ",")
1	a
2	b,c
3	E,C,D,d,d,D
select grp,group_concat(c separator "---->") from t1 group by grp;
grp	group_concat(c separator "---->")
1	a
2	b---->c
3	E---->C---->D---->d---->d---->D
select grp,group_concat(c order by c) from t1 group by grp;
grp	group_concat(c order by c)
1	a
2	b,c
3	C,D,d,d,D,E
select grp,group_concat(c order by c desc) from t1 group by grp;
grp	group_concat(c order by c desc)
1	a
2	c,b
3	E,D,d,d,D,C
select grp,group_concat(d order by a) from t1 group by grp;
grp	group_concat(d order by a)
1	a
2	a,b
3	a,b,b,d,d,c
select grp,group_concat(d order by a desc) from t1 group by grp;
grp	group_concat(d order by a desc)
1	a
2	b,a
3	c,d,d,b,b,a
select grp,group_concat(a order by a,d+c-ascii(c)-a) from t1 group by grp;
grp	group_concat(a order by a,d+c-ascii(c)-a)
1	1
2	2,3
3	4,5,6,7,8,9
select grp,group_concat(a order by d+c-ascii(c),a) from t1 group by grp;
grp	group_concat(a order by d+c-ascii(c),a)
1	1
2	3,2
3	7,8,4,6,9,5
select grp,group_concat(c order by 1) from t1 group by grp;
grp	group_concat(c order by 1)
1	a
2	b,c
3	C,D,d,d,D,E
select grp,group_concat(distinct c order by c) from t1 group by grp;
grp	group_concat(distinct c order by c)
1	a
2	b,c
3	C,D,E
select grp,group_concat(distinct c order by c desc) from t1 group by grp;
grp	group_concat(distinct c order by c desc)
1	a
2	c,b
3	E,D,C
explain extended select grp,group_concat(distinct c order by c desc) from t1 group by grp;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	100.00	Using filesort
Warnings:
Note	1003	select `test`.`t1`.`grp` AS `grp`,group_concat(distinct `test`.`t1`.`c` order by `test`.`t1`.`c` DESC separator ',') AS `group_concat(distinct c order by c desc)` from `test`.`t1` group by `test`.`t1`.`grp`
select grp,group_concat(c order by c separator ",") from t1 group by grp;
grp	group_concat(c order by c separator ",")
1	a
2	b,c
3	C,D,d,d,D,E
select grp,group_concat(c order by c desc separator ",") from t1 group by grp;
grp	group_concat(c order by c desc separator ",")
1	a
2	c,b
3	E,D,d,d,D,C
select grp,group_concat(distinct c order by c separator ",") from t1 group by grp;
grp	group_concat(distinct c order by c separator ",")
1	a
2	b,c
3	C,D,E
explain extended select grp,group_concat(distinct c order by c separator ",") from t1 group by grp;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	100.00	Using filesort
Warnings:
Note	1003	select `test`.`t1`.`grp` AS `grp`,group_concat(distinct `test`.`t1`.`c` order by `test`.`t1`.`c` ASC separator ',') AS `group_concat(distinct c order by c separator ",")` from `test`.`t1` group by `test`.`t1`.`grp`
select grp,group_concat(distinct c order by c desc separator ",") from t1 group by grp;
grp	group_concat(distinct c order by c desc separator ",")
1	a
2	c,b
3	E,D,C
select grp,group_concat(c order by grp desc) from t1 group by grp order by grp;
grp	group_concat(c order by grp desc)
1	a
2	c,b
3	D,d,d,D,C,E
select grp, group_concat(a separator "")+0 from t1 group by grp;
grp	group_concat(a separator "")+0
1	1
2	23
3	456789
select grp, group_concat(a separator "")+0.0 from t1 group by grp;
grp	group_concat(a separator "")+0.0
1	1.0
2	23.0
3	456789.0
select grp, ROUND(group_concat(a separator "")) from t1 group by grp;
grp	ROUND(group_concat(a separator ""))
1	1
2	23
3	456789
drop table t1;
create table t1 (grp int, c char(10));
insert into t1 values (1,NULL),(2,"b"),(2,NULL),(3,"E"),(3,NULL),(3,"D"),(3,NULL),(3,NULL),(3,"D"),(4,""),(5,NULL);
select grp,group_concat(c order by c) from t1 group by grp;
grp	group_concat(c order by c)
1	NULL
2	b
3	D,D,E
4	
5	NULL
set group_concat_max_len = 4;
select grp,group_concat(c) from t1 group by grp;
grp	group_concat(c)
1	NULL
2	b
3	D,D,
4	
5	NULL
Warnings:
Warning	1260	1 line(s) were cut by GROUP_CONCAT()
show warnings;
Level	Code	Message
Warning	1260	1 line(s) were cut by GROUP_CONCAT()
set group_concat_max_len = 1024;
select group_concat(sum(c)) from t1 group by grp;
ERROR HY000: Invalid use of group function
select grp,group_concat(c order by 2) from t1 group by grp;
ERROR 42S22: Unknown column '2' in 'order clause'
drop table t1;
create table t1 ( URL_ID int(11), URL varchar(80));
create table t2 ( REQ_ID int(11), URL_ID int(11));
insert into t1 values (4,'www.host.com'), (5,'www.google.com'),(5,'www.help.com');
insert into t2 values (1,4), (5,4), (5,5);
select REQ_ID, Group_Concat(URL) as URL from t1, t2 where
t2.URL_ID = t1.URL_ID group by REQ_ID;
REQ_ID	URL
1	X
5	X,X,X
select REQ_ID, Group_Concat(URL) as URL, Min(t1.URL_ID) urll,
Max(t1.URL_ID) urlg from t1, t2 where t2.URL_ID = t1.URL_ID group by REQ_ID;
REQ_ID	URL	urll	urlg
1	X	4	4
5	X,X,X	4	5
drop table t1;
drop table t2;
create table t1 (id int, name varchar(16));
insert into t1 values (1,'longername'),(1,'evenlongername');
select ifnull(group_concat(concat(t1.id, ':', t1.name)), 'shortname') as 'without distinct: how it should be' from t1;
without distinct: how it should be
1:longername,1:evenlongername
select distinct ifnull(group_concat(concat(t1.id, ':', t1.name)), 'shortname') as 'with distinct: cutoff at length of shortname' from t1;
with distinct: cutoff at length of shortname
1:longername,1:evenlongername
drop table t1;
create table t1(id int);
create table t2(id int);
insert into t1 values(0),(1);
select group_concat(t1.id) FROM t1,t2;
group_concat(t1.id)
NULL
drop table t1;
drop table t2;
create table t1 (bar varchar(32));
insert into t1 values('test1'),('test2');
select group_concat(bar order by concat(bar,bar)) from t1;
group_concat(bar order by concat(bar,bar))
test1,test2
select group_concat(bar order by concat(bar,bar) desc) from t1;
group_concat(bar order by concat(bar,bar) desc)
test2,test1
select bar from t1 having group_concat(bar)='';
bar
select bar from t1 having instr(group_concat(bar), "test") > 0;
bar
test1
select bar from t1 having instr(group_concat(bar order by concat(bar,bar) desc), "test2,test1") > 0;
bar
test1
drop table t1;
create table t1 (a int, a1 varchar(10));
create table t2 (a0 int);
insert into t1 values (0,"a"),(0,"b"),(1,"c");
insert into t2 values (1),(2),(3);
select  group_concat(a1 order by (t1.a IN (select a0 from t2))) from t1;
group_concat(a1 order by (t1.a IN (select a0 from t2)))
b,a,c
select  group_concat(a1 order by (t1.a)) from t1;
group_concat(a1 order by (t1.a))
b,a,c
drop table t1, t2;
CREATE TABLE t1 (id1 tinyint(4) NOT NULL, id2 tinyint(4) NOT NULL);
INSERT INTO t1 VALUES (1, 1),(1, 2),(1, 3),(1, 4),(1, 5),(2, 1),(2, 2),(2, 3);
CREATE TABLE t2 (id1 tinyint(4) NOT NULL);
INSERT INTO t2 VALUES (1),(2),(3),(4),(5);
SELECT t1.id1, GROUP_CONCAT(t1.id2 ORDER BY t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 AND t1.id1=1 GROUP BY t1.id1;
id1	concat_id
1	1,2,3,4,5
SELECT t1.id1, GROUP_CONCAT(t1.id2 ORDER BY t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	1,2,3,4,5
2	1,2,3
SELECT t1.id1, GROUP_CONCAT(t1.id2 ORDER BY t1.id2 DESC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	5,4,3,2,1
2	3,2,1
SELECT t1.id1, GROUP_CONCAT(t1.id2 ORDER BY 6-t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	5,4,3,2,1
2	3,2,1
SELECT t1.id1, GROUP_CONCAT(t1.id2,6-t1.id2 ORDER BY 6-t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	51,42,33,24,15
2	33,24,15
SELECT t1.id1, GROUP_CONCAT(t1.id2,6-t1.id2 ORDER BY 6-t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	51,42,33,24,15
2	33,24,15
SELECT t1.id1, GROUP_CONCAT(t1.id2,"/",6-t1.id2 ORDER BY 1+0,6-t1.id2,t1.id2 ASC) AS concat_id FROM t1, t2 WHERE t1.id1 = t2.id1 GROUP BY t1.id1;
id1	concat_id
1	5/1,4/2,3/3,2/4,1/5
2	3/3,2/4,1/5
drop table t1,t2;
create table t1 (s1 char(10), s2 int not null);
insert into t1 values ('a',2),('b',2),('c',1),('a',3),('b',4),('c',4);
select distinct s1 from t1 order by s2,s1;
s1
c
a
b
select group_concat(distinct s1) from t1;
group_concat(distinct s1)
a,b,c
select group_concat(distinct s1 order by s2) from t1 where s2 < 4;
group_concat(distinct s1 order by s2)
c,b,a
select group_concat(distinct s1 order by s2) from t1;
group_concat(distinct s1 order by s2)
c,b,a,c
drop table t1;
create table t1 (a int, c int);
insert into t1 values (1, 2), (2, 3), (2, 4), (3, 5);
create table t2 (a int, c int);
insert into t2 values (1, 5), (2, 4), (3, 3), (3,3);
select group_concat(c) from t1;
group_concat(c)
2,3,4,5
select group_concat(c order by (select c from t2 where t2.a=t1.a limit 1)) as grp from t1;
grp
5,4,3,2
select group_concat(c order by (select mid(group_concat(c order by a),1,5) from t2 where t2.a=t1.a)) as grp from t1;
grp
5,4,3,2
select group_concat(c order by (select mid(group_concat(c order by a),1,5) from t2 where t2.a=t1.a) desc) as grp from t1;
grp
2,4,3,5
select t1.a, group_concat(c order by (select c from t2 where t2.a=t1.a limit 1)) as grp from t1 group by 1;
a	grp
1	2
2	4,3
3	5
select t1.a, group_concat(c order by (select mid(group_concat(c order by a),1,5) from t2 where t2.a=t1.a)) as grp from t1 group by 1;
a	grp
1	2
2	4,3
3	5
select t1.a, group_concat(c order by (select mid(group_concat(c order by a),1,5) from t2 where t2.a=t1.a) desc) as grp from t1 group by 1;
a	grp
1	2
2	4,3
3	5
select group_concat(c order by (select concat(5-t1.c,group_concat(c order by a)) from t2 where t2.a=t1.a)) as grp from t1;
grp
5,4,3,2
select group_concat(c order by (select concat(t1.c,group_concat(c)) from t2 where a=t1.a)) as grp from t1;
grp
2,3,4,5
select a,c,(select group_concat(c order by a) from t2 where a=t1.a) as grp from t1 order by grp;
a	c	grp
3	5	3,3
2	3	4
2	4	4
1	2	5
drop table t1,t2;
CREATE TABLE t1 ( a int );
CREATE TABLE t2 ( a int );
INSERT INTO t1 VALUES (1), (2);
INSERT INTO t2 VALUES (1), (2);
SELECT GROUP_CONCAT(t1.a*t2.a ORDER BY t2.a) FROM t1, t2 GROUP BY t1.a;
GROUP_CONCAT(t1.a*t2.a ORDER BY t2.a)
1,2
2,4
DROP TABLE t1, t2;
CREATE TABLE t1 (a char(4));
INSERT INTO t1 VALUES ('John'), ('Anna'), ('Bill');
SELECT GROUP_CONCAT(a SEPARATOR '||') AS names FROM t1 
HAVING names LIKE '%An%';
names
John||Anna||Bill
SELECT GROUP_CONCAT(a SEPARATOR '###') AS names FROM t1 
HAVING LEFT(names, 1) ='J';
names
John###Anna###Bill
DROP TABLE t1;
CREATE TABLE t1 ( a int, b TEXT );
INSERT INTO t1 VALUES (1,'First Row'), (2,'Second Row');
SELECT GROUP_CONCAT(b ORDER BY b) FROM t1 GROUP BY a;
GROUP_CONCAT(b ORDER BY b)
First Row
Second Row
DROP TABLE t1;
CREATE TABLE t1 (A_ID INT NOT NULL,A_DESC CHAR(3) NOT NULL,PRIMARY KEY (A_ID));
INSERT INTO t1 VALUES (1,'ABC'), (2,'EFG'), (3,'HIJ');
CREATE TABLE t2 (A_ID INT NOT NULL,B_DESC CHAR(3) NOT NULL,PRIMARY KEY (A_ID,B_DESC));
INSERT INTO t2 VALUES (1,'A'),(1,'B'),(3,'F');
SELECT t1.A_ID, GROUP_CONCAT(t2.B_DESC) AS B_DESC FROM t1 LEFT JOIN t2 ON t1.A_ID=t2.A_ID GROUP BY t1.A_ID ORDER BY t1.A_DESC;
A_ID	B_DESC
1	A,B
2	NULL
3	F
DROP TABLE t1;
DROP TABLE t2;
create table t1 (a int, b text);
insert into t1 values (1, 'bb'), (1, 'ccc'), (1, 'a'), (1, 'bb'), (1, 'ccc');
insert into t1 values (2, 'BB'), (2, 'CCC'), (2, 'A'), (2, 'BB'), (2, 'CCC');
select group_concat(b) from t1 group by a;
group_concat(b)
bb,ccc,a,bb,ccc
BB,CCC,A,BB,CCC
select group_concat(distinct b) from t1 group by a;
group_concat(distinct b)
bb,ccc,a
BB,CCC,A
select group_concat(b order by b) from t1 group by a;
group_concat(b order by b)
a,bb,bb,ccc,ccc
A,BB,BB,CCC,CCC
select group_concat(distinct b order by b) from t1 group by a;
group_concat(distinct b order by b)
a,bb,ccc
A,BB,CCC
set local group_concat_max_len=4;
select group_concat(b) from t1 group by a;
group_concat(b)
bb,c
BB,C
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(distinct b) from t1 group by a;
group_concat(distinct b)
bb,c
BB,C
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(b order by b) from t1 group by a;
group_concat(b order by b)
a,bb
A,BB
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(distinct b order by b) from t1 group by a;
group_concat(distinct b order by b)
a,bb
A,BB
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
insert into t1 values (1, concat(repeat('1', 300), '2')), 
(1, concat(repeat('1', 300), '2')), (1, concat(repeat('0', 300), '1')), 
(2, concat(repeat('1', 300), '2')), (2, concat(repeat('1', 300), '2')), 
(2, concat(repeat('0', 300), '1'));
set local group_concat_max_len=1024;
select group_concat(b) from t1 group by a;
group_concat(b)
bb,ccc,a,bb,ccc,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
BB,CCC,A,BB,CCC,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
select group_concat(distinct b) from t1 group by a;
group_concat(distinct b)
bb,ccc,a,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
BB,CCC,A,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
select group_concat(b order by b) from t1 group by a;
group_concat(b order by b)
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,a,bb,bb,ccc,ccc
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,A,BB,BB,CCC,CCC
select group_concat(distinct b order by b) from t1 group by a;
group_concat(distinct b order by b)
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,a,bb,ccc
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,A,BB,CCC
set local group_concat_max_len=400;
select group_concat(b) from t1 group by a;
group_concat(b)
bb,ccc,a,bb,ccc,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111
BB,CCC,A,BB,CCC,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,1111111111111111111111111111111111111111111111111111111111111111111111111111111111
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(distinct b) from t1 group by a;
group_concat(distinct b)
bb,ccc,a,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
BB,CCC,A,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(b order by b) from t1 group by a;
group_concat(b order by b)
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
select group_concat(distinct b order by b) from t1 group by a;
group_concat(distinct b order by b)
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
Warnings:
Warning	1260	2 line(s) were cut by GROUP_CONCAT()
drop table t1;
create table t1 (a varchar(255) character set cp1250 collate cp1250_general_ci,
b varchar(255) character set koi8r);
insert into t1 values ('xxx','yyy');
select collation(a) from t1;
collation(a)
cp1250_general_ci
select collation(group_concat(a)) from t1;
collation(group_concat(a))
cp1250_general_ci
create table t2 select group_concat(a) as a from t1;
show create table t2;
Table	Create Table
t2	CREATE TABLE `t2` (
  `a` varchar(400) CHARACTER SET cp1250 DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
select collation(group_concat(a,_koi8r'test')) from t1;
collation(group_concat(a,_koi8r'test'))
cp1250_general_ci
select collation(group_concat(a,_koi8r 0xC1C2)) from t1;
ERROR HY000: Illegal mix of collations (cp1250_general_ci,IMPLICIT) and (koi8r_general_ci,COERCIBLE) for operation 'group_concat'
select collation(group_concat(a,b)) from t1;
ERROR HY000: Illegal mix of collations (cp1250_general_ci,IMPLICIT) and (koi8r_general_ci,IMPLICIT) for operation 'group_concat'
drop table t1;
drop table t2;
CREATE TABLE t1 (a CHAR(10) CHARACTER SET cp850);
INSERT INTO t1 VALUES ('ภ');
SELECT a FROM t1;
a
ภ
SELECT GROUP_CONCAT(a) FROM t1;
GROUP_CONCAT(a)
ภ
DROP TABLE t1;
CREATE TABLE t1 (id int);
SELECT GROUP_CONCAT(id) AS gc FROM t1 HAVING gc IS NULL;
gc
NULL
DROP TABLE t1;
create table t2 (a int, b int);
insert into t2 values (1,1), (2,2);
select  b x, (select group_concat(x) from t2) from  t2;
x	(select group_concat(x) from t2)
1	1,1
2	2,2
drop table t2;
create table t1 (d int not null auto_increment,primary key(d), a int, b int, c int);
insert into t1(a,b) values (1,3), (1,4), (1,2), (2,7), (1,1), (1,2), (2,3), (2,3);
select d,a,b from t1 order by a;
d	a	b
1	1	3
2	1	4
3	1	2
5	1	1
6	1	2
4	2	7
7	2	3
8	2	3
explain select a, group_concat(b) from t1 group by a with rollup;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	8	Using filesort
select a, group_concat(b) from t1 group by a with rollup;
a	group_concat(b)
1	3,4,2,1,2
2	7,3,3
NULL	3,4,2,1,2,7,3,3
select a, group_concat(distinct b) from t1 group by a with rollup;
a	group_concat(distinct b)
1	3,4,2,1
2	7,3
NULL	3,4,2,1,7
select a, group_concat(b order by b) from t1 group by a with rollup;
a	group_concat(b order by b)
1	1,2,2,3,4
2	3,3,7
NULL	1,2,2,3,3,3,4,7
select a, group_concat(distinct b order by b) from t1 group by a with rollup;
a	group_concat(distinct b order by b)
1	1,2,3,4
2	3,7
NULL	1,2,3,4,7
drop table t1;
create table t1 (a char(3), b char(20), primary key (a, b));
insert into t1 values ('ABW', 'Dutch'), ('ABW', 'English');
select group_concat(a) from t1 group by b;
group_concat(a)
ABW
ABW
drop table t1;
CREATE TABLE t1 (
aID smallint(5) unsigned NOT NULL auto_increment,
sometitle varchar(255) NOT NULL default '',
bID smallint(5) unsigned NOT NULL,
PRIMARY KEY  (aID),
UNIQUE KEY sometitle (sometitle)
);
INSERT INTO t1 SET sometitle = 'title1', bID = 1;
INSERT INTO t1 SET sometitle = 'title2', bID = 1;
CREATE TABLE t2 (
bID smallint(5) unsigned NOT NULL auto_increment,
somename varchar(255) NOT NULL default '',
PRIMARY KEY  (bID),
UNIQUE KEY somename (somename)
);
INSERT INTO t2 SET somename = 'test';
SELECT COUNT(*), GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
FROM t1 JOIN t2 ON t1.bID = t2.bID;
COUNT(*)	GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
2	test
INSERT INTO t2 SET somename = 'test2';
SELECT COUNT(*), GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
FROM t1 JOIN t2 ON t1.bID = t2.bID;
COUNT(*)	GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
2	test
DELETE FROM t2 WHERE somename = 'test2';
SELECT COUNT(*), GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
FROM t1 JOIN t2 ON t1.bID = t2.bID;
COUNT(*)	GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |')
2	test
DROP TABLE t1,t2;
select * from (select group_concat('c') from DUAL) t;
group_concat('c')
c
create table t1 ( a int not null default 0);
select * from (select group_concat(a) from t1) t2;
group_concat(a)
NULL
select group_concat('x') UNION ALL select 1;
group_concat('x')
x
1
drop table t1;
CREATE TABLE t1 (id int, a varchar(9));
INSERT INTO t1 VALUES
(2, ''), (1, ''), (2, 'x'), (1, 'y'), (3, 'z'), (3, '');
SELECT GROUP_CONCAT(a) FROM t1;
GROUP_CONCAT(a)
,,x,y,z,
SELECT GROUP_CONCAT(a ORDER BY a) FROM t1;
GROUP_CONCAT(a ORDER BY a)
,,,x,y,z
SELECT GROUP_CONCAT(a) FROM t1 GROUP BY id;
GROUP_CONCAT(a)
,y
,x
z,
SELECT GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY id;
GROUP_CONCAT(a ORDER BY a)
,y
,x
,z
DROP TABLE t1;
create table t1(f1 int);
insert into t1 values(1),(2),(3);
select f1, group_concat(f1+1) from t1 group by f1 with rollup;
f1	group_concat(f1+1)
1	2
2	3
3	4
NULL	2,3,4
select count(distinct (f1+1)) from t1 group by f1 with rollup;
count(distinct (f1+1))
1
1
1
3
drop table t1;
create table t1 (f1 int unsigned, f2 varchar(255));
insert into t1 values (1,repeat('a',255)),(2,repeat('b',255));
select f2,group_concat(f1) from t1 group by f2;
Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
def	test	t1	t1	f2	f2	253	255	255	Y	0	0	8
def					group_concat(f1)	253	400	1	Y	128	0	63
f2	group_concat(f1)
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	1
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb	2
drop table t1;
set names latin1;
create table t1 (a char, b char);
insert into t1 values ('a', 'a'), ('a', 'b'), ('b', 'a'), ('b', 'b');
create table t2 select group_concat(b) as a from t1 where a = 'a';
create table t3 (select group_concat(a) as a from t1 where a = 'a') union
(select group_concat(b) as a from t1 where a = 'b');
select charset(a) from t2;
charset(a)
latin1
select charset(a) from t3;
charset(a)
latin1
latin1
drop table t1, t2, t3;
set names default;
create table t1 (c1 varchar(10), c2 int);
select charset(group_concat(c1 order by c2)) from t1;
charset(group_concat(c1 order by c2))
latin1
drop table t1;
CREATE TABLE t1 (a INT(10), b LONGTEXT, PRIMARY KEY (a));
SET GROUP_CONCAT_MAX_LEN = 20000000;
INSERT INTO t1 VALUES (1,REPEAT(CONCAT('A',CAST(CHAR(0) AS BINARY),'B'), 40000));
INSERT INTO t1 SELECT a + 1, b FROM t1;
SELECT a, CHAR_LENGTH(b) FROM t1;
a	CHAR_LENGTH(b)
1	120000
2	120000
SELECT CHAR_LENGTH( GROUP_CONCAT(b) ) FROM t1;
CHAR_LENGTH( GROUP_CONCAT(b) )
240001
SET GROUP_CONCAT_MAX_LEN = 1024;
DROP TABLE t1;
CREATE TABLE t1 (a int, b int);
INSERT INTO t1 VALUES (2,1), (1,2), (2,2), (1,3);
SELECT GROUP_CONCAT(a), x 
FROM (SELECT a, GROUP_CONCAT(b) x FROM t1 GROUP BY a) AS s
GROUP BY x;
GROUP_CONCAT(a)	x
2	1,2
1	2,3
DROP TABLE t1;
set names utf8;
create table t1
(
x text character set utf8 not null,
y integer not null
);
insert into t1 values (repeat('a', 1022), 0), (repeat(_utf8 0xc3b7, 4), 0);
set group_concat_max_len= 1022 + 10;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1032	1031	1027	aaaaaaa,รทรทรทรท	C3B7C3B7C3B7
set group_concat_max_len= 1022 + 9;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1031	1031	1027	aaaaaaa,รทรทรทรท	C3B7C3B7C3B7
set group_concat_max_len= 1022 + 8;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1030	1029	1026	aaaaaaaa,รทรทรท	C3B7C3B7C3B7
set group_concat_max_len= 1022 + 7;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1029	1029	1026	aaaaaaaa,รทรทรท	C3B7C3B7C3B7
set group_concat_max_len= 1022 + 6;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1028	1027	1025	aaaaaaaaa,รทรท	612CC3B7C3B7
set group_concat_max_len= 1022 + 5;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1027	1027	1025	aaaaaaaaa,รทรท	612CC3B7C3B7
set group_concat_max_len= 1022 + 4;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1026	1025	1024	aaaaaaaaaa,รท	6161612CC3B7
set group_concat_max_len= 1022 + 3;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1025	1025	1024	aaaaaaaaaa,รท	6161612CC3B7
set group_concat_max_len= 1022 + 2;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1024	1023	1023	aaaaaaaaaaa,	61616161612C
set group_concat_max_len= 1022 + 1;
select @x:=group_concat(x) from t1 group by y;
select @@group_concat_max_len, length(@x), char_length(@x), right(@x,12), right(HEX(@x),12);
@@group_concat_max_len	length(@x)	char_length(@x)	right(@x,12)	right(HEX(@x),12)
1023	1023	1023	aaaaaaaaaaa,	61616161612C
drop table t1;
set group_concat_max_len=1024;
set names latin1;
create table t1 (f1 int unsigned, f2 varchar(255));
insert into t1 values (1,repeat('a',255)),(2,repeat('b',255));
select f2,group_concat(f1) from t1 group by f2;
Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
def	test	t1	t1	f2	f2	253	255	255	Y	0	0	8
def					group_concat(f1)	252	1024	1	Y	128	0	63
f2	group_concat(f1)
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	1
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb	2
drop table t1;
