如要删除三张表的联合信息，使用MYSQL的左连接方法：LEFT JOIN ON
例如，删除三张表中张三的所有数据：
delete student,sc,stu from student left join sc on student.sno = sc.sno left join stu on sc.sno = stu.sno where student.sname = ‘张三‘;
MYSQL删除三张表的联合信息
原文：https://www.cnblogs.com/hjd21/p/12944346.html
