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4d4ac0ede3
Major re-write of code yet has to be done, to circumvent assigning of UNIT to current select and to deal better with offset, limit.
270 lines
7.9 KiB
Plaintext
270 lines
7.9 KiB
Plaintext
drop table if exists t1,t2,t3;
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CREATE TABLE t1 (a int not null, b char (10) not null);
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insert into t1 values(1,'a'),(2,'b'),(3,'c'),(3,'c');
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CREATE TABLE t2 (a int not null, b char (10) not null);
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insert into t2 values (3,'c'),(4,'d'),(5,'f'),(6,'e');
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select a,b from t1 union select a,b from t2;
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a b
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1 a
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2 b
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3 c
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4 d
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5 f
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6 e
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select a,b from t1 union all select a,b from t2;
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a b
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1 a
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2 b
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3 c
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3 c
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3 c
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4 d
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5 f
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6 e
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select a,b from t1 union all select a,b from t2 order by b;
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a b
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1 a
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2 b
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3 c
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3 c
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3 c
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4 d
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6 e
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5 f
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select a,b from t1 union all select a,b from t2 union select 7,'g';
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a b
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1 a
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2 b
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3 c
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3 c
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3 c
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4 d
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5 f
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6 e
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7 g
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select 0,'#' union select a,b from t1 union all select a,b from t2 union select 7,'gg';
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0 #
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0 #
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1 a
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2 b
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3 c
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3 c
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3 c
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4 d
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5 f
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6 e
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7 g
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select a,b from t1 union select a,b from t1;
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a b
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1 a
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2 b
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3 c
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select 't1',b,count(*) from t1 group by b UNION select 't2',b,count(*) from t2 group by b;
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t1 b count(*)
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t1 a 1
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t1 b 1
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t1 c 2
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t2 c 1
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t2 d 1
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t2 e 1
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t2 f 1
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(select a,b from t1 limit 2) union all (select a,b from t2 order by a) limit 4;
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a b
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1 a
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2 b
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3 c
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4 d
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(select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1);
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a b
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1 a
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2 b
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3 c
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(select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc;
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a b
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3 c
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2 b
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1 a
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(select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by t1.b;
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Table 't1' from one of SELECT's can not be used in global ORDER clause
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explain (select a,b from t1 limit 2) union all (select a,b from t2 order by a limit 1) order by b desc;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4
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2 UNION t2 ALL NULL NULL NULL NULL 4 Using filesort
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select found_rows();
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found_rows()
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0
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explain select a,b from t1 union all select a,b from t2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4
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2 UNION t2 ALL NULL NULL NULL NULL 4
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explain select xx from t1 union select 1;
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Unknown column 'xx' in 'field list'
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explain select a,b from t1 union select 1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 4
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2 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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explain select 1 union select a,b from t1 union select 1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY NULL NULL NULL NULL NULL NULL NULL No tables used
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2 UNION t1 ALL NULL NULL NULL NULL 4
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3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
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explain select a,b from t1 union select 1 limit 0;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
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2 UNION NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
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select a,b from t1 into outfile 'skr' union select a,b from t2;
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Wrong usage of UNION and INTO
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select a,b from t1 order by a union select a,b from t2;
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Wrong usage of UNION and ORDER BY
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insert into t3 select a from t1 order by a union select a from t2;
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Wrong usage of UNION and ORDER BY
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create table t3 select a,b from t1 union select a from t2;
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The used SELECT statements have a different number of columns
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select a,b from t1 union select a from t2;
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The used SELECT statements have a different number of columns
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select * from t1 union select a from t2;
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The used SELECT statements have a different number of columns
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select a from t1 union select * from t2;
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The used SELECT statements have a different number of columns
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select * from t1 union select SQL_BUFFER_RESULT * from t2;
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Wrong usage/placement of 'SQL_BUFFER_RESULT'
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create table t3 select a,b from t1 union all select a,b from t2;
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insert into t3 select a,b from t1 union all select a,b from t2;
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replace into t3 select a,b as c from t1 union all select a,b from t2;
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drop table t1,t2,t3;
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CREATE TABLE t1 (
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`pseudo` char(35) NOT NULL default '',
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`pseudo1` char(35) NOT NULL default '',
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`same` tinyint(1) unsigned NOT NULL default '1',
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PRIMARY KEY (`pseudo1`),
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KEY `pseudo` (`pseudo`)
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) TYPE=MyISAM;
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INSERT INTO t1 (pseudo,pseudo1,same) VALUES ('joce', 'testtt', 1),('joce', 'tsestset', 1),('dekad', 'joce', 1);
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SELECT pseudo FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo FROM t1 WHERE pseudo='joce';
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pseudo
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dekad
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joce
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SELECT pseudo1 FROM t1 WHERE pseudo1='joce' UNION SELECT pseudo1 FROM t1 WHERE pseudo='joce';
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pseudo1
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joce
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testtt
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tsestset
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SELECT * FROM t1 WHERE pseudo1='joce' UNION SELECT * FROM t1 WHERE pseudo='joce' order by pseudo desc,pseudo1 desc;
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pseudo pseudo1 same
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joce tsestset 1
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joce testtt 1
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dekad joce 1
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SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION SELECT pseudo FROM t1 WHERE pseudo1='joce';
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pseudo1
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testtt
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tsestset
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dekad
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SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION ALL SELECT pseudo FROM t1 WHERE pseudo1='joce';
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pseudo1
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testtt
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tsestset
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dekad
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SELECT pseudo1 FROM t1 WHERE pseudo='joce' UNION SELECT 1;
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pseudo1
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testtt
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tsestset
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1
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drop table t1;
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create table t1 (a int);
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create table t2 (a int);
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insert into t1 values (1),(2),(3),(4),(5);
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insert into t2 values (11),(12),(13),(14),(15);
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(select * from t1 limit 2) union (select * from t2 limit 3) limit 4;
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a
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1
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2
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11
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12
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(select * from t1 limit 2) union (select * from t2 limit 3);
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a
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1
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2
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11
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12
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13
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(select * from t1 limit 2) union (select * from t2 limit 20,3);
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a
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1
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2
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set SQL_SELECT_LIMIT=2;
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(select * from t1 limit 1) union (select * from t2 limit 3);
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a
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1
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11
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set SQL_SELECT_LIMIT=DEFAULT;
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drop table t1,t2;
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select * union select 1;
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No tables used
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select 1 as a,(select a union select a);
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a (select a union select a)
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1 1
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drop table if exists t1,t2;
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CREATE TABLE t1 ( id int(3) unsigned default '0') TYPE=MyISAM;
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INSERT INTO t1 (id) VALUES("1");
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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;
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INSERT INTO t2 (id, id_master, text1, text2) VALUES("1", "1",
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"foo1", "bar1");
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INSERT INTO t2 (id, id_master, text1, text2) VALUES("2", "1",
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"foo2", "bar2");
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INSERT INTO t2 (id, id_master, text1, text2) VALUES("3", "1", NULL,
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"bar3");
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INSERT INTO t2 (id, id_master, text1, text2) VALUES("4", "1",
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"foo4", "bar4");
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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;
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id_master id text1 text2
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1 1 NULL ABCDE
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1 1 bar1
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1 2 bar2
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1 3 NULL bar3
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1 4 bar4
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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;
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id_master id text1 text2
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1 1 ABCDE ABCDE
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1 1 foo1 bar1
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1 2 foo2 bar2
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1 3 NULL bar3
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1 4 foo4 bar4
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drop table if exists t1,t2;
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(SELECT 1,3) UNION (SELECT 2,1) ORDER BY (SELECT 2);
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1 3
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1 3
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2 1
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create table t1 (a int not null primary key auto_increment, b int, key(b));
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create table t2 (a int not null primary key auto_increment, b int);
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insert into t1 (b) values (1),(2),(2),(3);
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insert into t2 (b) values (10),(11),(12),(13);
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explain (select * from t1 where a=1) union (select * from t2 where a=1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 const PRIMARY PRIMARY 4 const 1
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2 UNION t2 const PRIMARY PRIMARY 4 const 1
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(select * from t1 where a=5) union (select * from t2 where a=1);
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a b
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1 10
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(select * from t1 where a=5 and a=6) union (select * from t2 where a=1);
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a b
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1 10
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(select t1.a,t1.b from t1,t2 where t1.a=5) union (select * from t2 where a=1);
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a b
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1 10
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(select * from t1 where a=1) union (select t1.a,t2.a from t1,t2 where t1.a=t2.a);
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a b
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1 1
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2 2
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3 3
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4 4
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explain (select * from t1 where a=1 and b=10) union (select t1.a,t2.a from t1,t2 where t1.a=t2.a);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
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2 UNION t1 index PRIMARY PRIMARY 4 NULL 4 Using index
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2 UNION t2 index PRIMARY PRIMARY 4 NULL 4 Using where; Using index
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explain (select * from t1 where a=1) union (select * from t1 where b=1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 const PRIMARY PRIMARY 4 const 1
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2 UNION t1 ref b b 5 const 1 Using where
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drop table t1,t2;
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