SQL：如何删除行;当从具有多个返回的另一个表中保护“WHERE”时

Question

查询

    DELETE FROM TEMPSchedules 
           WHERE StudentID = ( Select StudentID 
                               From Students 
                               Where Ref = 'H1007')

错误消息

  

子查询返回的值超过1。这是不允许的   子查询跟随=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =或当子查询用作   表达。

问题

现在的问题是每个“Ref Group”都附加了1个以上的学生。那我应该怎么处理呢。 感谢

Answer 1

  DELETE FROM TEMPSchedules 
           WHERE StudentID  in ( Select distinct StudentID 
                               From Students 
                               Where Ref = 'H1007')

Answer 2

DELETE TEMPSchedules
From Students 
Where Students.Ref = 'H1007' and Students.StudentID=TEMPSchedules.StudentID

Answer 3

以下SQL语句仅从＆＃34;＆＃34; StudentID＆＃34;＆＃34;中选择DISTINCT值。 ＆＃34;＆＃34;＆＃34;＆＃34;＆＃34;＆＃34;表格Ref =＆＃39; H1007＆＃39;： SELECT DISTINCT StudentID FROM Students;