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 Row 4 was cut by GROUP_CONCAT() show warnings; Level Code Message Warning 1260 Row 4 was 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 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) a,bb,ccc A,BB,CCC 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 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 4 was cut by GROUP_CONCAT() select group_concat(distinct b) from t1 group by a; group_concat(distinct b) a,bb A,BB Warnings: Warning 1260 Row 3 was cut by GROUP_CONCAT() Warning 1260 Row 6 was 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 Row 3 was cut by GROUP_CONCAT() Warning 1260 Row 6 was 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 Row 3 was cut by GROUP_CONCAT() Warning 1260 Row 6 was 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) 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,a,bb,ccc 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111112,A,BB,CCC 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 Row 7 was cut by GROUP_CONCAT() Warning 1260 Row 14 was cut by GROUP_CONCAT() select group_concat(distinct b) from t1 group by a; group_concat(distinct b) 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 4 was 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 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 4 was 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 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 4 was 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 COLLATE cp1250_general_ci DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci 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 1,2,3,4 2 3,7 NULL 1,2,3,4,7 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 0 0 8 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 0 0 8 f2 group_concat(f1) aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 1 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 2 drop table t1; CREATE TABLE t1(a TEXT, b CHAR(20)); INSERT INTO t1 VALUES ("one.1","one.1"),("two.2","two.2"),("one.3","one.3"); SELECT GROUP_CONCAT(DISTINCT UCASE(a)) FROM t1; GROUP_CONCAT(DISTINCT UCASE(a)) ONE.1,ONE.3,TWO.2 SELECT GROUP_CONCAT(DISTINCT UCASE(b)) FROM t1; GROUP_CONCAT(DISTINCT UCASE(b)) ONE.1,ONE.3,TWO.2 DROP TABLE t1; CREATE TABLE t1( a VARCHAR( 10 ), b INT ); INSERT INTO t1 VALUES ( repeat( 'a', 10 ), 1), ( repeat( 'b', 10 ), 2); SET group_concat_max_len = 20; SELECT GROUP_CONCAT( a ) FROM t1; GROUP_CONCAT( a ) aaaaaaaaaa,bbbbbbbbb Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() SELECT GROUP_CONCAT( DISTINCT a ) FROM t1; GROUP_CONCAT( DISTINCT a ) aaaaaaaaaa,bbbbbbbbb Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() SELECT GROUP_CONCAT( a ORDER BY b ) FROM t1; GROUP_CONCAT( a ORDER BY b ) aaaaaaaaaa,bbbbbbbbb Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() SELECT GROUP_CONCAT( DISTINCT a ORDER BY b ) FROM t1; GROUP_CONCAT( DISTINCT a ORDER BY b ) aaaaaaaaaa,bbbbbbbbb Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() SET group_concat_max_len = DEFAULT; DROP TABLE t1; SET group_concat_max_len= 65535; CREATE TABLE t1( a TEXT, b INTEGER ); INSERT INTO t1 VALUES ( 'a', 0 ), ( 'b', 1 ); SELECT GROUP_CONCAT( a ORDER BY b ) FROM t1; GROUP_CONCAT( a ORDER BY b ) a,b SELECT GROUP_CONCAT(DISTINCT a ORDER BY b) FROM t1; GROUP_CONCAT(DISTINCT a ORDER BY b) a,b SELECT GROUP_CONCAT(DISTINCT a) FROM t1; GROUP_CONCAT(DISTINCT a) a,b SET group_concat_max_len= 10; SELECT GROUP_CONCAT(a ORDER BY b) FROM t1; GROUP_CONCAT(a ORDER BY b) a,b SELECT GROUP_CONCAT(DISTINCT a ORDER BY b) FROM t1; GROUP_CONCAT(DISTINCT a ORDER BY b) a,b SELECT GROUP_CONCAT(DISTINCT a) FROM t1; GROUP_CONCAT(DISTINCT a) a,b SET group_concat_max_len= 65535; CREATE TABLE t2( a TEXT ); INSERT INTO t2 VALUES( REPEAT( 'a', 5000 ) ); INSERT INTO t2 VALUES( REPEAT( 'b', 5000 ) ); INSERT INTO t2 VALUES( REPEAT( 'a', 5000 ) ); SELECT LENGTH( GROUP_CONCAT( DISTINCT a ) ) FROM t2; LENGTH( GROUP_CONCAT( DISTINCT a ) ) 10001 CREATE TABLE t3( a TEXT, b INT ); INSERT INTO t3 VALUES( REPEAT( 'a', 65534 ), 1 ); INSERT INTO t3 VALUES( REPEAT( 'a', 65535 ), 2 ); INSERT IGNORE INTO t3 VALUES( REPEAT( 'a', 65536 ), 3 ); Warnings: Warning 1265 Data truncated for column 'a' at row 1 SELECT LENGTH( GROUP_CONCAT( a ) ) FROM t3 WHERE b = 1; LENGTH( GROUP_CONCAT( a ) ) 65534 SELECT LENGTH( GROUP_CONCAT( a ) ) FROM t3 WHERE b = 2; LENGTH( GROUP_CONCAT( a ) ) 65535 SELECT LENGTH( GROUP_CONCAT( a ) ) FROM t3 WHERE b = 3; LENGTH( GROUP_CONCAT( a ) ) 65535 SET group_concat_max_len= DEFAULT; DROP TABLE t1, t2, t3; set names latin1; create table t1 (id int, name varchar(20)) DEFAULT CHARSET=utf8; insert into t1 (id, name) values (1, "๓ra"); insert into t1 (id, name) values (2, "๓ra"); select b.id, group_concat(b.name) from t1 a, t1 b group by b.id; id group_concat(b.name) 1 ๓ra,๓ra 2 ๓ra,๓ra drop table t1; create table t1(a bit not null); insert ignore into t1 values (), (), (); Warnings: Warning 1364 Field 'a' doesn't have a default value select group_concat(distinct a) from t1; group_concat(distinct a) 0 select group_concat(distinct a order by a) from t1; group_concat(distinct a order by a) 0 drop table t1; create table t1(a bit(2) not null); insert into t1 values (1), (0), (0), (3), (1); select group_concat(distinct a) from t1; group_concat(distinct a) 0,1,3 select group_concat(distinct a order by a) from t1; group_concat(distinct a order by a) 0,1,3 select group_concat(distinct a order by a desc) from t1; group_concat(distinct a order by a desc) 3,1,0 drop table t1; create table t1(a bit(2), b varchar(10), c bit); insert into t1 values (1, 'a', 0), (0, 'b', 1), (0, 'c', 0), (3, 'd', 1), (1, 'e', 1), (3, 'f', 1), (0, 'g', 1); select group_concat(distinct a, c) from t1; group_concat(distinct a, c) 00,01,10,11,31 select group_concat(distinct a, c order by a) from t1; group_concat(distinct a, c order by a) 00,01,11,10,31 select group_concat(distinct a, c) from t1; group_concat(distinct a, c) 00,01,10,11,31 select group_concat(distinct a, c order by a, c) from t1; group_concat(distinct a, c order by a, c) 00,01,10,11,31 select group_concat(distinct a, c order by a desc, c desc) from t1; group_concat(distinct a, c order by a desc, c desc) 31,11,10,01,00 drop table t1; create table t1 (f1 char(20)); insert into t1 values (''),(''); select group_concat(distinct f1) from t1; group_concat(distinct f1) select group_concat(f1) from t1; group_concat(f1) , drop table t1; CREATE TABLE t1 (a INT, b INT); INSERT INTO t1 VALUES (1, 1), (2, 2), (2, 3); SELECT GROUP_CONCAT(DISTINCT a ORDER BY b) FROM t1; GROUP_CONCAT(DISTINCT a ORDER BY b) 1,2 SELECT GROUP_CONCAT(DISTINCT a ORDER BY b DESC) FROM t1; GROUP_CONCAT(DISTINCT a ORDER BY b DESC) 2,1 SELECT GROUP_CONCAT(DISTINCT a) FROM t1; GROUP_CONCAT(DISTINCT a) 1,2 SELECT GROUP_CONCAT(DISTINCT a + 1 ORDER BY 3 - b) FROM t1; GROUP_CONCAT(DISTINCT a + 1 ORDER BY 3 - b) 3,2 SELECT GROUP_CONCAT(DISTINCT a + 1 ORDER BY b) FROM t1; GROUP_CONCAT(DISTINCT a + 1 ORDER BY b) 2,3 SELECT GROUP_CONCAT(a ORDER BY 3 - b) FROM t1; GROUP_CONCAT(a ORDER BY 3 - b) 2,2,1 CREATE TABLE t2 (a INT, b INT, c INT, d INT); INSERT INTO t2 VALUES (1,1, 1,1), (1,1, 2,2), (1,2, 2,1), (2,1, 1,2); SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY c, d) FROM t2; GROUP_CONCAT(DISTINCT a, b ORDER BY c, d) 11,21,12 SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY d, c) FROM t2; GROUP_CONCAT(DISTINCT a, b ORDER BY d, c) 11,12,21 CREATE TABLE t3 (a INT, b INT, c INT); INSERT INTO t3 VALUES (1, 1, 1), (2, 1, 2), (3, 2, 1); SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY b, c) FROM t3; GROUP_CONCAT(DISTINCT a, b ORDER BY b, c) 11,21,32 SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY c, b) FROM t3; GROUP_CONCAT(DISTINCT a, b ORDER BY c, b) 11,32,21 SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY a, b) FROM t1; GROUP_CONCAT(DISTINCT a, b ORDER BY a, b) 11,22,23 SELECT GROUP_CONCAT(DISTINCT b, a ORDER BY a, b) FROM t1; GROUP_CONCAT(DISTINCT b, a ORDER BY a, b) 11,22,32 SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY b, a) FROM t1; GROUP_CONCAT(DISTINCT a, b ORDER BY b, a) 11,22,23 SELECT GROUP_CONCAT(DISTINCT b, a ORDER BY a, b) FROM t1; GROUP_CONCAT(DISTINCT b, a ORDER BY a, b) 11,22,32 SELECT GROUP_CONCAT(DISTINCT a ORDER BY a, b) FROM t1; GROUP_CONCAT(DISTINCT a ORDER BY a, b) 1,2 SELECT GROUP_CONCAT(DISTINCT b ORDER BY b, a) FROM t1; GROUP_CONCAT(DISTINCT b ORDER BY b, a) 1,2,3 SELECT GROUP_CONCAT(DISTINCT a, b ORDER BY a) FROM t1; GROUP_CONCAT(DISTINCT a, b ORDER BY a) 11,23,22 SELECT GROUP_CONCAT(DISTINCT b, a ORDER BY b) FROM t1; GROUP_CONCAT(DISTINCT b, a ORDER BY b) 11,22,32 DROP TABLE t1, t2, t3; CREATE TABLE t1(a INT); INSERT INTO t1 VALUES (),(); SELECT s1.d1 FROM ( SELECT t1.a as d1, GROUP_CONCAT(DISTINCT t1.a) AS d2 FROM t1 AS t1, t1 AS t2 GROUP BY 1 ) AS s1; d1 NULL DROP TABLE t1; CREATE TABLE t1 (a INT); CREATE TABLE t2 (a INT); INSERT INTO t1 VALUES(1); SELECT GROUP_CONCAT(DISTINCT t2.a) FROM t1 LEFT JOIN t2 ON t2.a = t1.a GROUP BY t1.a; GROUP_CONCAT(DISTINCT t2.a) NULL DROP TABLE t1, t2; CREATE TABLE t1 (a INT, KEY(a)); CREATE TABLE t2 (b INT); INSERT INTO t1 VALUES (NULL), (8), (2); INSERT INTO t2 VALUES (4), (10); SELECT 1 FROM t1 WHERE t1.a NOT IN ( SELECT GROUP_CONCAT(DISTINCT t1.a) FROM t1 WHERE t1.a IN ( SELECT b FROM t2 ) AND NOT t1.a >= (SELECT t1.a FROM t1 LIMIT 1) GROUP BY t1.a ); 1 1 1 1 DROP TABLE t1, t2; CREATE TABLE t1 (f1 INT); INSERT INTO t1 VALUES (),(); EXPLAIN EXTENDED SELECT 1 FROM (SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 100.00 1 PRIMARY ALL NULL NULL NULL NULL 4 100.00 Using join buffer (flat, BNL join) 2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort 2 DERIVED td ALL NULL NULL NULL NULL 2 100.00 Using join buffer (flat, BNL join) Warnings: Note 1003 /* select#1 */ select 1 AS `1` from (/* select#2 */ select distinct group_concat(`test`.`td`.`f1` separator ',') AS `GROUP_CONCAT(td.f1)` from `test`.`t1` join `test`.`t1` `td` group by `test`.`td`.`f1`) `d` join `test`.`t1` SELECT 1 FROM (SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1; 1 1 1 DROP TABLE t1; End of 5.0 tests # # Bug #52397: another crash with explain extended and group_concat # CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (0), (0); EXPLAIN EXTENDED SELECT 1 FROM (SELECT GROUP_CONCAT(t1.a ORDER BY t1.a ASC) FROM t1 t2, t1 GROUP BY t1.a) AS d; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY ALL NULL NULL NULL NULL 4 100.00 2 DERIVED t2 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort 2 DERIVED t1 ALL NULL NULL NULL NULL 2 100.00 Using join buffer (flat, BNL join) Warnings: Note 1003 /* select#1 */ select 1 AS `1` from (/* select#2 */ select group_concat(`test`.`t1`.`a` order by `test`.`t1`.`a` ASC separator ',') AS `GROUP_CONCAT(t1.a ORDER BY t1.a ASC)` from `test`.`t1` `t2` join `test`.`t1` group by `test`.`t1`.`a`) `d` DROP TABLE t1; End of 5.0 tests # # Bug #54476: crash when group_concat and 'with rollup' in prepared statements # CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (1), (2); PREPARE stmt FROM "SELECT GROUP_CONCAT(t1.a ORDER BY t1.a) FROM t1 JOIN t1 t2 GROUP BY t1.a WITH ROLLUP"; EXECUTE stmt; GROUP_CONCAT(t1.a ORDER BY t1.a) 1,1 2,2 1,1,2,2 EXECUTE stmt; GROUP_CONCAT(t1.a ORDER BY t1.a) 1,1 2,2 1,1,2,2 DEALLOCATE PREPARE stmt; DROP TABLE t1; # # Bug#57194 group_concat cause crash and/or invalid memory reads with type errors # CREATE TABLE t1(f1 int); INSERT INTO t1 values (0),(0); SELECT POLYGON((SELECT 1 FROM (SELECT 1 IN (GROUP_CONCAT(t1.f1)) FROM t1, t1 t GROUP BY t.f1 ) d)); ERROR HY000: Illegal parameter data type int for operation 'polygon' DROP TABLE t1; # # Bug#58396 group_concat and explain extended are still crashy # CREATE TABLE t1(a INT); EXPLAIN EXTENDED SELECT UPDATEXML('1', a, '1') FROM t1 ORDER BY (SELECT GROUP_CONCAT(1) FROM t1); ERROR HY000: Only constant XPATH queries are supported SHOW WARNINGS; Level Code Message Error 1105 Only constant XPATH queries are supported DROP TABLE t1; End of 5.1 tests DROP TABLE IF EXISTS t1, t2; CREATE TABLE t1 (a VARCHAR(6), b INT); CREATE TABLE t2 (a VARCHAR(6), b INT); INSERT INTO t1 VALUES ('111111', 1); INSERT INTO t1 VALUES ('222222', 2); INSERT INTO t1 VALUES ('333333', 3); INSERT INTO t1 VALUES ('444444', 4); INSERT INTO t1 VALUES ('555555', 5); SET group_concat_max_len = 5; SET @old_sql_mode = @@sql_mode, @@sql_mode = 'traditional'; SELECT GROUP_CONCAT(a), b FROM t1 GROUP BY b LIMIT 3; GROUP_CONCAT(a) b 11111 1 22222 2 33333 3 Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 3 was cut by GROUP_CONCAT() INSERT INTO t2 SELECT GROUP_CONCAT(a), b FROM t1 GROUP BY b; ERROR HY000: Row 1 was cut by GROUP_CONCAT() UPDATE t1 SET a = '11111' WHERE b = 1; UPDATE t1 SET a = '22222' WHERE b = 2; INSERT INTO t2 SELECT GROUP_CONCAT(a), b FROM t1 GROUP BY b; ERROR HY000: Row 3 was cut by GROUP_CONCAT() SET group_concat_max_len = DEFAULT; SET @@sql_mode = @old_sql_mode; DROP TABLE t1, t2; create table t1 (a char(1) character set utf8); insert into t1 values ('a'),('b'); select 1 from t1 where a in (select group_concat(a) from t1); 1 drop table t1; CREATE TABLE t1 (f1 VARCHAR(10)) ENGINE=MyISAM; INSERT INTO t1 VALUES ('a'),('b'); CREATE TABLE t2 (f2 VARCHAR(10)) ENGINE=MyISAM; INSERT INTO t2 VALUES ('c'); CREATE TABLE t3 (f3 VARCHAR(10)) ENGINE=MyISAM; INSERT INTO t3 VALUES ('d'),('e'); SELECT GROUP_CONCAT( f2 ORDER BY ( f2 IN ( SELECT f1 FROM t1 WHERE f1 <= f2 ) ) ) AS field FROM ( SELECT * FROM t2 ) AS sq2, t3 ORDER BY field; field c,c drop table t3, t2, t1; # # MDEV-7821 - Server crashes in Item_func_group_concat::fix_fields on 2nd # execution of PS # CREATE TABLE t1(a INT); INSERT INTO t1 VALUES(1),(2); PREPARE stmt FROM "SELECT GROUP_CONCAT(t1a.a ORDER BY 1, t1a.a=0) FROM t1 AS t1a, t1 AS t1b GROUP BY t1a.a"; EXECUTE stmt; GROUP_CONCAT(t1a.a ORDER BY 1, t1a.a=0) 1,1 2,2 EXECUTE stmt; GROUP_CONCAT(t1a.a ORDER BY 1, t1a.a=0) 1,1 2,2 DROP TABLE t1; # # WL#6098 Eliminate GROUP_CONCAT intermediate result limitation. # Bug#13387020 GROUP_CONCAT WITH ORDER BY RESULTS ARE TRUNCATED. # SET group_concat_max_len= 9999999; CREATE TABLE t1 (f1 LONGTEXT , f2 INTEGER); INSERT INTO t1 VALUES (REPEAT('a', 500000), 0), (REPEAT('b', 500000), 1), (REPEAT('c', 500000), 2); SELECT LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) FROM t1; LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) 1500002 SELECT LENGTH(GROUP_CONCAT(DISTINCT f1 ORDER BY f1 DESC)) FROM t1; LENGTH(GROUP_CONCAT(DISTINCT f1 ORDER BY f1 DESC)) 1500002 SELECT SUBSTRING(GROUP_CONCAT(DISTINCT f1 ORDER BY f1 DESC), 1, 5) FROM t1; SUBSTRING(GROUP_CONCAT(DISTINCT f1 ORDER BY f1 DESC), 1, 5) ccccc SELECT LENGTH(GROUP_CONCAT(DISTINCT f1)) FROM t1; LENGTH(GROUP_CONCAT(DISTINCT f1)) 1500002 SELECT LENGTH(GROUP_CONCAT(UPPER(f1) ORDER BY f2)) FROM t1; LENGTH(GROUP_CONCAT(UPPER(f1) ORDER BY f2)) 1500002 SELECT LENGTH(GROUP_CONCAT(DISTINCT UPPER(f1) ORDER BY f1)) FROM t1; LENGTH(GROUP_CONCAT(DISTINCT UPPER(f1) ORDER BY f1)) 1500002 SELECT SUBSTRING(GROUP_CONCAT(DISTINCT UPPER(f1) ORDER BY f1), 1, 5) FROM t1; SUBSTRING(GROUP_CONCAT(DISTINCT UPPER(f1) ORDER BY f1), 1, 5) AAAAA SELECT LENGTH(GROUP_CONCAT(DISTINCT UPPER(f1))) FROM t1; LENGTH(GROUP_CONCAT(DISTINCT UPPER(f1))) 1500002 CREATE TABLE t2 SELECT GROUP_CONCAT(f1 order by f2) FROM t1; SHOW CREATE TABLE t2; Table Create Table t2 CREATE TABLE `t2` ( `GROUP_CONCAT(f1 order by f2)` mediumtext DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci DROP TABLE t2; CREATE TABLE t2 SELECT GROUP_CONCAT(UPPER(f1) ORDER BY f2) FROM t1; SHOW CREATE TABLE t2; Table Create Table t2 CREATE TABLE `t2` ( `GROUP_CONCAT(UPPER(f1) ORDER BY f2)` mediumtext DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci DROP TABLE t2; SET group_concat_max_len= 1024; SELECT LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) FROM t1; LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) 1024 Warnings: Warning 1260 Row 2 was cut by GROUP_CONCAT() SET group_concat_max_len= 499999; SELECT LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) FROM t1 WHERE f2 = 0; LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) 499999 Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() SELECT LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) FROM t1 GROUP BY f2; LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) 499999 499999 499999 Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 3 was cut by GROUP_CONCAT() INSERT INTO t1 VALUES (REPEAT('a', 499999), 3), (REPEAT('b', 500000), 4); SELECT LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) FROM t1 GROUP BY f2; LENGTH(GROUP_CONCAT(f1 ORDER BY f2)) 499999 499999 499999 499999 499999 Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() Warning 1260 Row 2 was cut by GROUP_CONCAT() Warning 1260 Row 3 was cut by GROUP_CONCAT() Warning 1260 Row 5 was cut by GROUP_CONCAT() DROP TABLE t1; SET group_concat_max_len= DEFAULT; set session group_concat_max_len=1024; set max_session_mem_used=16*1024*1024; SELECT GROUP_CONCAT(concat(seq/1.1), concat(seq/1.1), concat(seq/1.1), concat(seq/1.1), concat(seq/1.1), concat(seq/1.1), concat(seq/1.1), concat(seq/1.1) ORDER BY 2,1,3,4,6,5,8,7) AS c FROM seq_1_to_200000; c 0.90910.90910.90910.90910.90910.90910.90910.9091,1.81821.81821.81821.81821.81821.81821.81821.8182,10.000010.000010.000010.000010.000010.000010.000010.0000,10.909110.909110.909110.909110.909110.909110.909110.9091,100.0000100.0000100.0000100.0000100.0000100.0000100.0000100.0000,100.9091100.9091100.9091100.9091100.9091100.9091100.9091100.9091,1000.00001000.00001000.00001000.00001000.00001000.00001000.00001000.0000,1000.90911000.90911000.90911000.90911000.90911000.90911000.90911000.9091,10000.000010000.000010000.000010000.000010000.000010000.000010000.000010000.0000,10000.909110000.909110000.909110000.909110000.909110000.909110000.909110000.9091,100000.0000100000.0000100000.0000100000.0000100000.0000100000.0000100000.0000100000.0000,100000.9091100000.9091100000.9091100000.9091100000.9091100000.9091100000.9091100000.9091,100001.8182100001.8182100001.8182100001.8182100001.8182100001.8182100001.8182100001.8182,100002.7273100002.7273100002.7273100002.7273100002.7273100002.7273100002.7273100002.7273,100003.6364100003. Warnings: Warning 1260 Row 15 was cut by GROUP_CONCAT() set max_session_mem_used=default; set session group_concat_max_len=default; SET group_concat_max_len= 8; CREATE TABLE t1 (a INT); INSERT t1 VALUES (1),(2); CREATE TABLE t2 (b DATE, c INT); INSERT t2 VALUES ('2019-12-04',1),('2020-03-28',2); CREATE TABLE t3 (d INT); INSERT t3 VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14); CREATE TABLE t4 (e INT); INSERT t4 VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14),(15); SELECT (SELECT MAX(a) FROM t1 WHERE t2_sq.c > 0) AS f, GROUP_CONCAT(t2_sq.b ORDER BY 1) AS gc FROM (SELECT t2_a.* FROM t2 AS t2_a, t2 AS t2_b) AS t2_sq, t3, t4 GROUP BY f; f gc 2 2019-12- Warnings: Warning 1260 Row 1 was cut by GROUP_CONCAT() DROP TABLE t1, t2, t3, t4; SET group_concat_max_len= default; # # Start of 10.2 tests # # # MDEV-10124 Incorrect usage of CUBE/ROLLUP and ORDER BY with GROUP_CONCAT(a ORDER BY a) # CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (10),(20),(30); SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP; a GROUP_CONCAT(a ORDER BY a) 10 10 20 20 30 30 NULL 10,20,30 CREATE VIEW v1 AS SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP; SELECT * FROM v1; a GROUP_CONCAT(a ORDER BY a) 10 10 20 20 30 30 NULL 10,20,30 DROP VIEW v1; SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30'; a GROUP_CONCAT(a ORDER BY a) NULL 10,20,30 CREATE VIEW v1 AS SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30'; SELECT * FROM v1; a GROUP_CONCAT(a ORDER BY a) NULL 10,20,30 DROP VIEW v1; SELECT * FROM (SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30') t1; a GROUP_CONCAT(a ORDER BY a) NULL 10,20,30 CREATE VIEW v1 AS SELECT * FROM (SELECT a,GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30') t1; SELECT * FROM v1; a GROUP_CONCAT(a ORDER BY a) NULL 10,20,30 DROP VIEW v1; SELECT (SELECT GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30'); (SELECT GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30') 10,20,30 CREATE VIEW v1 AS SELECT (SELECT GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY a WITH ROLLUP HAVING GROUP_CONCAT(a ORDER BY a)='10,20,30'); SELECT * FROM v1; Name_exp_1 10,20,30 DROP VIEW v1; DROP TABLE t1; # # MDEV-4677 GROUP_CONCAT not showing any output with group_concat_max_len >= 4Gb # set group_concat_max_len=1024*1024*1024*4; Warnings: Warning 1292 Truncated incorrect group_concat_max_len value: '4294967296' create table t1 (i int, j int); insert into t1 values (1,1),(1,2); select i, group_concat(j) from t1 group by i; i group_concat(j) 1 1,2 drop table t1; # # End of 10.2 tests # # # Start of 10.3 tests # drop table if exists t1, t2; create table t1 (grp int, a bigint unsigned, c char(10) , d char(10) not null); insert into t1 values (1,1,NULL,"a"); insert into t1 values (1,10,"b","a"); insert into t1 values (1,11,"c","a"); insert into t1 values (2,2,"c","a"); insert into t1 values (2,3,"b","b"); insert into t1 values (3,4,"E","a"); insert into t1 values (3,5,"C","b"); insert into t1 values (3,6,"D","c"); insert into t1 values (3,7,"E","c"); select grp,group_concat(c) from t1 group by grp; grp group_concat(c) 1 b,c 2 c,b 3 E,C,D,E select grp,group_concat(c limit 1 ) from t1 group by grp; grp group_concat(c limit 1 ) 1 b 2 c 3 E select grp,group_concat(c limit 1,1 ) from t1 group by grp; grp group_concat(c limit 1,1 ) 1 c 2 b 3 C select grp,group_concat(c limit 1,10 ) from t1 group by grp; grp group_concat(c limit 1,10 ) 1 c 2 b 3 C,D,E select grp,group_concat(c limit 1000) from t1 group by grp; grp group_concat(c limit 1000) 1 b,c 2 c,b 3 E,C,D,E select group_concat(grp limit 0) from t1; group_concat(grp limit 0) select group_concat(grp limit "sdjadjs") from t1 --error ER_PARSE_ERROR select grp,group_concat(c limit 5.5) from t1 group by grp ; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '"sdjadjs") from t1 --error ER_PARSE_ERROR select grp,group_concat(c limit 5.5...' at line 1 select grp,group_concat(distinct c limit 1,10 ) from t1 group by grp; grp group_concat(distinct c limit 1,10 ) 1 c 2 c 3 D,E select grp,group_concat(c order by a) from t1 group by grp; grp group_concat(c order by a) 1 b,c 2 c,b 3 E,C,D,E select grp,group_concat(c order by a limit 2 ) from t1 group by grp; grp group_concat(c order by a limit 2 ) 1 b,c 2 c,b 3 E,C select grp,group_concat(c order by a limit 1,1 ) from t1 group by grp; grp group_concat(c order by a limit 1,1 ) 1 c 2 b 3 C select grp,group_concat(c order by c) from t1 group by grp; grp group_concat(c order by c) 1 b,c 2 b,c 3 C,D,E,E select grp,group_concat(c order by c limit 2) from t1 group by grp; grp group_concat(c order by c limit 2) 1 b,c 2 b,c 3 C,D select grp,group_concat(c order by c desc) from t1 group by grp; grp group_concat(c order by c desc) 1 c,b 2 c,b 3 E,E,D,C select grp,group_concat(c order by c desc limit 2) from t1 group by grp; grp group_concat(c order by c desc limit 2) 1 c,b 2 c,b 3 E,E # # Empty results for group concat as offset is greater than the rows # for a group # select grp,group_concat(distinct c limit 10,1 ) from t1 group by grp; grp group_concat(distinct c limit 10,1 ) 1 2 3 drop table t1; create table t2 (a int, b varchar(10)); insert into t2 values(1,'a'),(1,'b'),(NULL,'c'),(2,'x'),(2,'y'); select group_concat(a,b limit 2) from t2; group_concat(a,b limit 2) 1a,1b set @x=4; prepare STMT from 'select group_concat(b limit ?) from t2'; execute STMT using @x; group_concat(b limit ?) a,b,c,x set @x=2; execute STMT using @x; group_concat(b limit ?) a,b set @x=1000; execute STMT using @x; group_concat(b limit ?) a,b,c,x,y set @x=0; execute STMT using @x; group_concat(b limit ?) set @x="adasfa"; execute STMT using @x; ERROR HY000: Limit only accepts integer values set @x=-1; execute STMT using @x; ERROR HY000: Incorrect arguments to EXECUTE set @x=4; prepare STMT from 'select group_concat(a,b limit ?) from t2'; execute STMT using @x; group_concat(a,b limit ?) 1a,1b,2x,2y drop table t2; # # MDEV-18943: Group Concat with limit not working with views # create table t1 (a int, b varchar(10)); insert into t1 values(1,'a'),(1,'b'),(NULL,'c'),(2,'x'),(2,'y'); select group_concat(a,b limit 2) from t1; group_concat(a,b limit 2) 1a,1b create view v1 as select group_concat(a,b limit 2) from t1; select * from v1; group_concat(a,b limit 2) 1a,1b drop view v1; drop table t1; # # End of 10.3 tests #