mysql点滴记录:mysql与oracle的确很多区别之处： 多表左链接链接： Select * FROM t1 LEFT JOIN (t2, t3, t4) ON (t2.a=t1.a AND t3.b=t1.b AND t4.c=t1.c) delete别名问题： 如： delete from student a where a.id in (1,2);