通过临时表循环获取记录值

Question

情景：

1. 从一个TableA中选择记录
2. 遍历表值
3. 根据每个记录的值
从另一个表（TableB）中删除

示例：

DECLARE @CustomerList TABLE (CustomerID bigint) 
INSERT INTO @CustomerList SELECT CustomerID FROM TableA WHERE CustomerID = @ParameterID

WHILE (SELECT COUNT(*) FROM @CustomerList) > 0
BEGIN
DELETE FROM [TableB]
WHERE [CustomerID] = @CustomerList.CustomerID -- challenge
END

挑战：

• 传递每个循环的CustomerID值

更新

• 想要使用循环的原因是有多个要执行的删除语句

Answer 1

为什么要循环？

Delete From [Table B]
 Where [CustomerID] in (Select CustomerID from TableA where SomeCondition=true)

好的，然后支持多次删除。您可以保留表变量

DECLARE @CustomerList TABLE (CustomerID bigint) 
INSERT INTO @CustomerList SELECT CustomerID FROM TableA WHERE CustomerID = @ParameterID

Delete From [Table B] Where [CustomerID] in (Select CustomerID from @CustomerList)
Delete From [Table C] Where [CustomerID] in (Select CustomerID from @CustomerList)

Answer 2

为什么你不能使用join而不是while。像下面的东西。

DELETE t
FROM TableB as t
join @CustomerList as c
on t.CustomerID = C.CustomerID;

Answer 3

我不确定你为什么需要临时表或循环。联接应该有效。

示例：

DELETE B
FROM TableB B
INNER JOIN TableA A
  ON B.CustomerID=A.CustomerID
WHERE A.CustomerID = @ParameterID