先上問題： 我這里有十個表，我要在這十個表中查詢字段tid = 40的結(jié)果 方法： 
SELECT * FROM `yle_forum_attachment_0` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_1` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_2` WHERE `tid` = '50'
union all 
SELECT * FROM `yle_forum_attachment_3` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_4` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_5` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_6` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_7` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_8` WHERE `tid` = '50' 
union all 
SELECT * FROM `yle_forum_attachment_9` WHERE `tid` = '50'
?注意：所有表的結(jié)構(gòu)必須一致才可以使用本方法！