SQL Server删除涉及两个表的查询

Question

所以我在SQL Server中有表A和B,分别在a和b列.我想在伪查询命令中执行以下操作,但我似乎无法弄明白.

我想要

DELETE FROM A 
WHERE a < 100 "and only if these selected (for deletion) values don't exist in column b in table B"

原因是我试图从表A中删除一些数据,但它给出了一个错误,说Aa和Bb中的值之间存在约束.

这是否涉及别名？令人困惑的是......

Answer 1

如果您使用的是SQL Server 2005或更高版本,请尝试此操作:

DELETE FROM TableA
WHERE a < 100 AND 
a NOT IN (SELECT B FROM TableB)

对于SQL Server 2000,这应该工作:

DELETE ta
FROM TableA as ta
LEFT JOIN TableB as tb
ON ta.a = tb.b
WHERE ta.a < 100 AND  tb.b IS NULL