mysql - 删除与依赖表没有任何链接的所有行

Question

我有两张 table 。一个是students，另一个是studentPerformance

students 表包含 id、name 和 email_id

studentPerformance 表包含 id、student_id、marks

我的问题是，如何从students表中删除所有在studentPerformance表中没有任何记录的学生？

我用 Google 搜索过，但没有找到任何合适的地方。

谢谢。

Answer 1

左连接:

 DELETE s 
 FROM Students AS s 
 LEFT JOIN StudentPerformance AS sp
  ON sp.student_id = s.id 
 WHERE sp.student_id IS NULL; -- where not match was found (no sp-row)

或不存在:

 DELETE s 
 FROM Students AS s 
 WHERE NOT EXISTS (SELECT 1 FROM StudentPerformance AS sp WHERE sp.student_id = s.id);