drop table if exists t1,t2,t3,t4,t5,t6; CREATE TABLE t1 (a int not null, b char (10) not null); insert into t1 values(1,'a'),(2,'b'),(3,'c'),(3,'c'); CREATE TABLE t2 (a int not null, b char (10) not null); insert into t2 values (3,'c'),(4,'d'),(5,'f'),(6,'e'); select a,b from t1 union select a,b from t2; a b 1 a 2 b 3 c 4 d 5 f 6 e select a,b from t1 union all select a,b from t2; a b 1 a 2 b 3 c 3 c 3 c 4 d 5 f 6 e select a,b from t1 union all select a,b from t2 order by b; a b 1 a 2 b 3 c 3 c 3 c 4 d 6 e 5 f select a,b from t1 union all select a,b from t2 union select 7,'g'; a b 1 a 2 b 3 c 3 c 3 c 4 d 5 f 6 e 7 g select 0,'#' union select a,b from t1 union all select a,b from t2 union select 7,'gg'; 0 # 0 # 1 a 2 b 3 c 3 c 3 c 4 d 5 f 6 e 7 gg select a,b from t1 union select a,b from t1; a b 1 a 2 b 3 c select 't1',b,count(*) from t1 group by b UNION select 't2',b,count(*) from t2 group by b; t1 b count(*) t1 a 1 t1 b 1 t1 c 2 t2 c 1 t2 d 1 t2 e 1 t2 f 1 (select a,b from t1 limit 2) union all (select a,b from t2 order by a) limit 4; a b 1 a 2 b 3 c 4 d (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1); a b 1 a 2 b 3 c (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc; a b 3 c 2 b 1 a (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by t1.b; ERROR 42000: Table 't1' from one of SELECT's can not be used in global ORDER clause explain extended (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 2 UNION t2 ALL NULL NULL NULL NULL 4 Using filesort Warnings: Note 1003 (select high_priority test.t1.a AS `a`,test.t1.b AS `b` from test.t1 limit 2) union all (select test.t2.a AS `a`,test.t2.b AS `b` from test.t2 order by test.t2.a limit 1) order by b desc (select sql_calc_found_rows a,b from t1 limit 2) union all (select a,b from t2 order by a) limit 2; a b 1 a 2 b select found_rows(); found_rows() 6 select sql_calc_found_rows a,b from t1 union all select a,b from t2 limit 2; a b 1 a 2 b select found_rows(); found_rows() 8 explain select a,b from t1 union all select a,b from t2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 2 UNION t2 ALL NULL NULL NULL NULL 4 explain select xx from t1 union select 1; ERROR 42S22: Unknown column 'xx' in 'field list' explain select a,b from t1 union select 1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 4 2 UNION NULL NULL NULL NULL NULL NULL NULL No tables used explain select 1 union select a,b from t1 union select 1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used 2 UNION t1 ALL NULL NULL NULL NULL 4 3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used explain select a,b from t1 union select 1 limit 0; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE 2 UNION NULL NULL NULL NULL NULL NULL NULL Impossible WHERE select a,b from t1 into outfile 'skr' union select a,b from t2; ERROR HY000: Wrong usage of UNION and INTO select a,b from t1 order by a union select a,b from t2; ERROR HY000: Wrong usage of UNION and ORDER BY insert into t3 select a from t1 order by a union select a from t2; ERROR HY000: Wrong usage of UNION and ORDER BY create table t3 select a,b from t1 union select a from t2; ERROR 21000: The used SELECT statements have a different number of columns select a,b from t1 union select a from t2; ERROR 21000: The used SELECT statements have a different number of columns select * from t1 union select a from t2; ERROR 21000: The used SELECT statements have a different number of columns select a from t1 union select * from t2; ERROR 21000: The used SELECT statements have a different number of columns select * from t1 union select SQL_BUFFER_RESULT * from t2; ERROR 42000: Wrong usage/placement of 'SQL_BUFFER_RESULT' create table t3 select a,b from t1 union all select a,b from t2; insert into t3 select a,b from t1 union all select a,b from t2; replace into t3 select a,b as c from t1 union all select a,b from t2; drop table t1,t2,t3; select * union select 1; ERROR HY000: No tables used select 1 as a,(select a union select a); a (select a union select a) 1 1 (select 1) union (select 2) order by 0; ERROR 42S22: Unknown column '0' in 'order clause' SELECT @a:=1 UNION SELECT @a:=@a+1; @a:=1 1 2 (SELECT 1) UNION (SELECT 2) ORDER BY (SELECT a); ERROR 42S22: Unknown column 'a' in 'field list' (SELECT 1,3) UNION (SELECT 2,1) ORDER BY (SELECT 2); 1 3 1 3 2 1 CREATE TABLE t1 ( `pseudo` char(35) NOT NULL default '', `pseudo1` char(35) NOT NULL default '', `same` tinyint(1) unsigned NOT NULL default '1', PRIMARY KEY (`pseudo1`), KEY `pseudo` (`pseudo`) ) TYPE=MyISAM; INSERT INTO t1 (pseudo,pseudo1,same) VALUES ('joce', 'testtt', 1),('joce', 'tsestset', 1),('dekad', 'joce', 1); SELECT pseudo FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo FROM t1 WHERE pseudo='joce'; pseudo dekad joce SELECT pseudo1 FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo1 FROM t1 WHERE pseudo='joce'; pseudo1 joce testtt tsestset SELECT * FROM t1 WHERE pseudo1='joce' UNION SELECT * FROM t1 WHERE pseudo='joce' order by pseudo desc,pseudo1 desc; pseudo pseudo1 same joce tsestset 1 joce testtt 1 dekad joce 1 SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION SELECT pseudo FROM t1 WHERE pseudo1='joce'; pseudo1 testtt tsestset dekad SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION ALL SELECT pseudo FROM t1 WHERE pseudo1='joce'; pseudo1 testtt tsestset dekad SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION SELECT 1; pseudo1 testtt tsestset 1 drop table t1; create table t1 (a int); create table t2 (a int); insert into t1 values (1),(2),(3),(4),(5); insert into t2 values (11),(12),(13),(14),(15); (select * from t1 limit 2) union (select * from t2 limit 3) limit 4; a 1 2 11 12 (select * from t1 limit 2) union (select * from t2 limit 3); a 1 2 11 12 13 (select * from t1 limit 2) union (select * from t2 limit 20,3); a 1 2 set SQL_SELECT_LIMIT=2; (select * from t1 limit 1) union (select * from t2 limit 3); a 1 11 set SQL_SELECT_LIMIT=DEFAULT; drop table t1,t2; CREATE TABLE t1 ( cid smallint(5) unsigned NOT NULL default '0', cv varchar(250) NOT NULL default '', PRIMARY KEY (cid), UNIQUE KEY cv (cv) ) ; INSERT INTO t1 VALUES (8,'dummy'); CREATE TABLE t2 ( cid bigint(20) unsigned NOT NULL auto_increment, cap varchar(255) NOT NULL default '', PRIMARY KEY (cid), KEY cap (cap) ) ; CREATE TABLE t3 ( gid bigint(20) unsigned NOT NULL auto_increment, gn varchar(255) NOT NULL default '', must tinyint(4) default NULL, PRIMARY KEY (gid), KEY gn (gn) ) ; INSERT INTO t3 VALUES (1,'V1',NULL); CREATE TABLE t4 ( uid bigint(20) unsigned NOT NULL default '0', gid bigint(20) unsigned default NULL, rid bigint(20) unsigned default NULL, cid bigint(20) unsigned default NULL, UNIQUE KEY m (uid,gid,rid,cid), KEY uid (uid), KEY rid (rid), KEY cid (cid), KEY container (gid,rid,cid) ) ; INSERT INTO t4 VALUES (1,1,NULL,NULL); CREATE TABLE t5 ( rid bigint(20) unsigned NOT NULL auto_increment, rl varchar(255) NOT NULL default '', PRIMARY KEY (rid), KEY rl (rl) ) ; CREATE TABLE t6 ( uid bigint(20) unsigned NOT NULL auto_increment, un varchar(250) NOT NULL default '', uc smallint(5) unsigned NOT NULL default '0', PRIMARY KEY (uid), UNIQUE KEY nc (un,uc), KEY un (un) ) ; INSERT INTO t6 VALUES (1,'test',8); SELECT t4.uid, t5.rl, t3.gn as g1, t4.cid, t4.gid as gg FROM t3, t6, t1, t4 left join t5 on t5.rid = t4.rid left join t2 on t2.cid = t4.cid WHERE t3.gid=t4.gid AND t6.uid = t4.uid AND t6.uc = t1.cid AND t1.cv = "dummy" AND t6.un = "test"; uid rl g1 cid gg 1 NULL V1 NULL 1 SELECT t4.uid, t5.rl, t3.gn as g1, t4.cid, t4.gid as gg FROM t3, t6, t1, t4 left join t5 on t5.rid = t4.rid left join t2 on t2.cid = t4.cid WHERE t3.gid=t4.gid AND t6.uid = t4.uid AND t3.must IS NOT NULL AND t6.uc = t1.cid AND t1.cv = "dummy" AND t6.un = "test"; uid rl g1 cid gg (SELECT t4.uid, t5.rl, t3.gn as g1, t4.cid, t4.gid as gg FROM t3, t6, t1, t4 left join t5 on t5.rid = t4.rid left join t2 on t2.cid = t4.cid WHERE t3.gid=t4.gid AND t6.uid = t4.uid AND t3.must IS NOT NULL AND t6.uc = t1.cid AND t1.cv = "dummy" AND t6.un = "test") UNION (SELECT t4.uid, t5.rl, t3.gn as g1, t4.cid, t4.gid as gg FROM t3, t6, t1, t4 left join t5 on t5.rid = t4.rid left join t2 on t2.cid = t4.cid WHERE t3.gid=t4.gid AND t6.uid = t4.uid AND t6.uc = t1.cid AND t1.cv = "dummy" AND t6.un = "test"); uid rl g1 cid gg 1 NULL V1 NULL 1 drop table t1,t2,t3,t4,t5,t6; CREATE TABLE t1 (a int not null, b char (10) not null); insert into t1 values(1,'a'),(2,'b'),(3,'c'),(3,'c'); CREATE TABLE t2 (a int not null, b char (10) not null); insert into t2 values (3,'c'),(4,'d'),(5,'f'),(6,'e'); create table t3 select a,b from t1 union select a,b from t2; create table t4 (select a,b from t1) union (select a,b from t2) limit 2; insert into t4 select a,b from t1 union select a,b from t2; insert into t3 (select a,b from t1) union (select a,b from t2) limit 2; select * from t3; a b 1 a 2 b 3 c 4 d 5 f 6 e 1 a 2 b select * from t4; a b 1 a 2 b 1 a 2 b 3 c 4 d 5 f 6 e drop table t1,t2,t3,t4; create table t1 (a int); insert into t1 values (1),(2),(3); create table t2 (a int); insert into t2 values (3),(4),(5); (SELECT SQL_CALC_FOUND_ROWS * FROM t1) UNION all (SELECT * FROM t2) LIMIT 1; a 1 select found_rows(); found_rows() 6 (SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1) UNION all (SELECT * FROM t2) LIMIT 2; a 1 3 select found_rows(); found_rows() 4 (SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1) UNION all (SELECT * FROM t2); a 1 3 4 5 select found_rows(); found_rows() 4 (SELECT SQL_CALC_FOUND_ROWS * FROM t1) UNION all (SELECT * FROM t2 LIMIT 1); a 1 2 3 3 select found_rows(); found_rows() 4 (SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1) UNION SELECT * FROM t2 LIMIT 1; ERROR 42000: You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1 UNION all SELECT * FROM t2 LIMIT 2; a 1 3 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 UNION all SELECT * FROM t2 LIMIT 2; a 1 2 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 UNION SELECT * FROM t2 LIMIT 2; a 1 2 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 UNION SELECT * FROM t2 LIMIT 100; a 1 2 3 4 5 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 100 UNION SELECT * FROM t2; a 1 2 3 4 5 select found_rows(); found_rows() 5 SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1 UNION SELECT * FROM t2; a 1 3 4 5 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 LIMIT 1 UNION SELECT * FROM t2 LIMIT 2; a 1 3 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 UNION SELECT * FROM t2 LIMIT 2,2; a 3 4 select found_rows(); found_rows() 6 SELECT SQL_CALC_FOUND_ROWS * FROM t1 limit 2,2 UNION SELECT * FROM t2; a 3 4 5 select found_rows(); found_rows() 5 SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY a desc LIMIT 1; a 5 (SELECT * FROM t1 ORDER by a) UNION ALL (SELECT * FROM t2 ORDER BY a) ORDER BY A desc LIMIT 4; a 5 4 3 3 (SELECT * FROM t1) UNION all (SELECT SQL_CALC_FOUND_ROWS * FROM t2) LIMIT 1; ERROR 42000: Wrong usage/placement of 'SQL_CALC_FOUND_ROWS' drop table t1,t2; CREATE TABLE t1 ( id int(3) unsigned default '0') TYPE=MyISAM; INSERT INTO t1 (id) VALUES("1"); CREATE TABLE t2 ( id int(3) unsigned default '0', id_master int(5) default '0', text1 varchar(5) default NULL, text2 varchar(5) default NULL) TYPE=MyISAM; INSERT INTO t2 (id, id_master, text1, text2) VALUES("1", "1", "foo1", "bar1"); INSERT INTO t2 (id, id_master, text1, text2) VALUES("2", "1", "foo2", "bar2"); INSERT INTO t2 (id, id_master, text1, text2) VALUES("3", "1", NULL, "bar3"); INSERT INTO t2 (id, id_master, text1, text2) VALUES("4", "1", "foo4", "bar4"); SELECT 1 AS id_master, 1 AS id, NULL AS text1, 'ABCDE' AS text2 UNION SELECT id_master, t2.id, text1, text2 FROM t1 LEFT JOIN t2 ON t1.id = t2.id_master; id_master id text1 text2 1 1 NULL ABCDE 1 1 foo1 bar1 1 2 foo2 bar2 1 3 NULL bar3 1 4 foo4 bar4 SELECT 1 AS id_master, 1 AS id, 'ABCDE' AS text1, 'ABCDE' AS text2 UNION SELECT id_master, t2.id, text1, text2 FROM t1 LEFT JOIN t2 ON t1.id = t2.id_master; id_master id text1 text2 1 1 ABCDE ABCDE 1 1 foo1 bar1 1 2 foo2 bar2 1 3 NULL bar3 1 4 foo4 bar4 drop table if exists t1,t2; create table t1 (a int not null primary key auto_increment, b int, key(b)); create table t2 (a int not null primary key auto_increment, b int); insert into t1 (b) values (1),(2),(2),(3); insert into t2 (b) values (10),(11),(12),(13); explain extended (select * from t1 where a=1) union (select * from t2 where a=1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 const PRIMARY PRIMARY 4 const 1 2 UNION t2 const PRIMARY PRIMARY 4 const 1 Warnings: Note 1003 (select high_priority test.t1.a AS `a`,test.t1.b AS `b` from test.t1 where (test.t1.a = 1)) union (select test.t2.a AS `a`,test.t2.b AS `b` from test.t2 where (test.t2.a = 1)) (select * from t1 where a=5) union (select * from t2 where a=1); a b 1 10 (select * from t1 where a=5 and a=6) union (select * from t2 where a=1); a b 1 10 (select t1.a,t1.b from t1,t2 where t1.a=5) union (select * from t2 where a=1); a b 1 10 (select * from t1 where a=1) union (select t1.a,t2.a from t1,t2 where t1.a=t2.a); a b 1 1 2 2 3 3 4 4 explain (select * from t1 where a=1 and b=10) union (select straight_join t1.a,t2.a from t1,t2 where t1.a=t2.a); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables 2 UNION t1 index PRIMARY PRIMARY 4 NULL 4 Using index 2 UNION t2 index PRIMARY PRIMARY 4 NULL 3 Using where; Using index explain (select * from t1 where a=1) union (select * from t1 where b=1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 const PRIMARY PRIMARY 4 const 1 2 UNION t1 ref b b 5 const 1 Using where drop table t1,t2; create table t1 ( id int not null auto_increment, primary key (id) ,user_name text ); create table t2 ( id int not null auto_increment, primary key (id) ,group_name text ); create table t3 ( id int not null auto_increment, primary key (id) ,user_id int ,index user_idx (user_id) ,foreign key (user_id) references users(id) ,group_id int ,index group_idx (group_id) ,foreign key (group_id) references groups(id) ); insert into t1 (user_name) values ('Tester'); insert into t2 (group_name) values ('Group A'); insert into t2 (group_name) values ('Group B'); insert into t3 (user_id, group_id) values (1,1); select 1 'is_in_group', a.user_name, c.group_name, b.id from t1 a, t3 b, t2 c where a.id = b.user_id and b.group_id = c.id UNION select 0 'is_in_group', a.user_name, c.group_name, null from t1 a, t2 c; is_in_group user_name group_name id 1 Tester Group A 1 0 Tester Group A NULL 0 Tester Group B NULL drop table t1, t2, t3; create table t1 (mat_id MEDIUMINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, matintnum CHAR(6) NOT NULL, test MEDIUMINT UNSIGNED NULL); create table t2 (mat_id MEDIUMINT UNSIGNED NOT NULL, pla_id MEDIUMINT UNSIGNED NOT NULL); insert into t1 values (NULL, 'a', 1), (NULL, 'b', 2), (NULL, 'c', 3), (NULL, 'd', 4), (NULL, 'e', 5), (NULL, 'f', 6), (NULL, 'g', 7), (NULL, 'h', 8), (NULL, 'i', 9); insert into t2 values (1, 100), (1, 101), (1, 102), (2, 100), (2, 103), (2, 104), (3, 101), (3, 102), (3, 105); SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id union SELECT 0, 0; pla_id matintnum 100 a 101 a 102 a 103 b 104 b 105 c 0 0 drop table t1, t2; create table t1 SELECT "a" as a UNION select "aa" as a; select * from t1; a a aa show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `a` char(2) NOT NULL default '' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT 12 as a UNION select "aa" as a; select * from t1; a 12 aa show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `a` char(2) NOT NULL default '' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT 12 as a UNION select 12.2 as a; select * from t1; a 12.0 12.2 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `a` double(4,1) NOT NULL default '0.0' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t2 (it1 tinyint, it2 tinyint not null, i int not null, ib bigint, f float, d double, y year, da date, dt datetime, sc char(10), sv varchar(10), b blob, tx text); insert into t2 values (NULL, 1, 3, 4, 1.5, 2.5, 1972, '1972-10-22', '1972-10-22 11:50', 'testc', 'testv', 'tetetetetest', 'teeeeeeeeeeeest'); create table t1 SELECT it2 from t2 UNION select it1 from t2; select * from t1; it2 1 NULL show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `it2` tinyint(4) default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT it2 from t2 UNION select i from t2; select * from t1; it2 1 3 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `it2` int(11) NOT NULL default '0' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT i from t2 UNION select f from t2; select * from t1; i 3 1.5 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `i` double default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT f from t2 UNION select d from t2; select * from t1; f 1.5 2.5 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `f` double default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT ib from t2 UNION select f from t2; select * from t1; ib 4 1.5 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `ib` double default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT ib from t2 UNION select d from t2; select * from t1; ib 4 2.5 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `ib` double default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT f from t2 UNION select y from t2; select * from t1; f 1.5 1972 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `f` float default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT f from t2 UNION select da from t2; select * from t1; f 1.5 1972-10-22 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `f` char(12) binary default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT y from t2 UNION select da from t2; select * from t1; y 1972 1972-10-22 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `y` char(10) binary default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT y from t2 UNION select dt from t2; select * from t1; y 1972 1972-10-22 11:50:00 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `y` char(19) binary default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT da from t2 UNION select dt from t2; select * from t1; da 1972-10-22 00:00:00 1972-10-22 11:50:00 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `da` datetime default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT dt from t2 UNION select sc from t2; select * from t1; dt 1972-10-22 11:50:00 testc show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `dt` char(19) default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT dt from t2 UNION select sv from t2; select * from t1; dt 1972-10-22 11:50:00 testv show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `dt` char(19) default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT sc from t2 UNION select sv from t2; select * from t1; sc testc testv show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `sc` varchar(10) default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT dt from t2 UNION select b from t2; select * from t1; dt 1972-10-22 11:50:00 tetetetetest show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `dt` longblob ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT sv from t2 UNION select b from t2; select * from t1; sv testv tetetetetest show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `sv` longblob ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT i from t2 UNION select d from t2 UNION select b from t2; select * from t1; i 3 2.5 tetetetetest show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `i` blob ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT sv from t2 UNION select tx from t2; select * from t1; sv testv teeeeeeeeeeeest show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `sv` text ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 SELECT b from t2 UNION select tx from t2; select * from t1; b tetetetetest teeeeeeeeeeeest show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `b` longblob ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1,t2; create table t1 (d decimal(10,1)); create table t2 (d decimal(10,9)); insert into t1 values ("100000000.0"); insert into t2 values ("1.23456780"); create table t3 select * from t2 union select * from t1; select * from t3; d 1.234567800 100000000.0 show create table t3; Table Create Table t3 CREATE TABLE `t3` ( `d` decimal(10,9) default NULL ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1,t2,t3; create table t1 select 1 union select -1; select * from t1; 1 1 -1 show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `1` bigint(1) NOT NULL default '0' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1; create table t1 select _latin1"test" union select _latin2"testt" ; ERROR HY000: Illegal mix of collations (latin1_swedish_ci,COERCIBLE) and (latin2_general_ci,COERCIBLE) for operation 'UNION' create table t1 select _latin2"test" union select _latin2"testt" ; show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `test` char(5) character set latin2 NOT NULL default '' ) TYPE=MyISAM DEFAULT CHARSET=latin1 drop table t1;