如何删除涉及多个表的单个表中的行

Question

嗨，我刚接触 sql，我很难删除记录。我需要从教师为“MARSHALL”的 subjcode 表中删除所有记录。我使用了这个查询，但我不工作：

delete
from subjcode
where (
        select sa.sno
        from subjcode sa,
            teacher,
            course
        where teacher.tname = 'MARSHALL'
            and teacher.tno = course.tno
            and course.cno = sa.cno
        ) = subjcode.sno;

还有表格和它的列：

subjcode: sno,cno,score

course: cno,tno,cname

teacher:tno,tname

我知道我只需要 tname、tno 和 cno，但我不知道正确的查询。请帮帮我谢谢

Answer 1

您可以使用 join 删除：

delete s
from subjcode s
join course c on s.cno = c.cno
join teacher t on t.tno = c.tno
where t.tname = 'MARSHALL';

请参阅此内容：

• https://dev.mysql.com/doc/refman/5.7/en/delete.html

Answer 2

试试这个：

delete s 
from subjcode s 
join course c on s.cno = c.cno 
join teacher t on c.tno = t.tno
where t.tname = 'MARSHALL';