请教:Mysql中下面两句话有什么不同?
(1)select * from shumu where z13_ZTFLH like 'P2%' or 'TB22%' or 'TU198%' or 'TP7%'
(2)select * from shumu where z13_ZTFLH like 'P2%'
or z13_ZTFLH like 'TB22%'
or z13_ZTFLH like 'TU198%'
or z13_ZTFLH like 'TP7%'
(1)select * from shumu where z13_ZTFLH like 'P2%' or 'TB22%' or 'TU198%' or 'TP7%'
(2)select * from shumu where z13_ZTFLH like 'P2%'
or z13_ZTFLH like 'TB22%'
or z13_ZTFLH like 'TU198%'
or z13_ZTFLH like 'TP7%'
1、相当于
select * from shumu
2、要满足
z13_ZTFLH like 'P2%'
or z13_ZTFLH like 'TB22%'
or z13_ZTFLH like 'TU198%'
or z13_ZTFLH like 'TP7%'
条件的记录才被查询出来
select * from shumu?
经测试,2的返回结果比1多,有些不解;
逻辑不对地。结果都不一样。z13_ZTFLH like 'P2%' or ('TB22%') or ('TU198%') or ('TP7%' )
z13_ZTFLH like 'P2%' or (true) or (true) or (true)
=
select * from shumu where z13_ZTFLH like 'P2%' or true or true or true
怎么不是返回全表记录