1.多表查询

　　SELECT a.id,catid,thumb,title FROM v9_gamedown as a LEFT JOIN v9_gamedown_data as b ON a.id=b.id WHERE a.status=99 and b.artist="‘.$artist.‘" limit 0,‘.$num

2.把一张表中的字段移动到另一张表

　　update v9_gamedown_data as a set a.n_language = (select language from v9_gamedown as b where b.id = a.id)
　　update v9_gamedown_data as a set a.n_thumb2 = (select thumb2 from v9_gamedown as b where b.id = a.id)

mysql 语句总结