drop table if exists test1 ; create table test1 ( id int (11), name char(20) )ENGINE=MyISAM DEFAULT CHARSET=utf8 ; drop table if exists test2 ; create table test2 ( id int (11), name char(20) )ENGINE=MyISAM DEFAULT CHARSET=utf8 ; insert into test1 values( 1,'javaliujie' ) ; insert into test1 values( 2,NULL ) ; insert into test1 values( 3,NULL ) ; insert into test1 values( 4,'' ) ; insert into test1 values( 5,'' ) ; insert into test2 values( 1,'javaliujie' ) ; insert into test2 values( 2,NULL ) ; insert into test2 values( 3,NULL ) ; insert into test2 values( 4,NULL ) ; insert into test2 values( 5,'' ) ; mysql> select * from test1,test2 where test1.id=test2.id and test1.name=test2.name ; +------+------------+------+------------+ | id | name | id | name | +------+------------+------+------------+ | 1 | javaliujie | 1 | javaliujie | | 5 | | 5 | | +------+------------+------+------------+ 2 rows in set (0.00 sec)
MYSQL中在select时对NULL值的发现
MYSQL中,在select时对两个同为NULL值的字段竟然不匹配。记录一下。
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转载自javaliujie.iteye.com/blog/1553077
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