我们可以在 CROSS APPLY 中加入表格吗？

Question

我的查询是：

CROSS APPLY(
SELECT SUM(Payment)
FROM (
    SELECT TOP(ABS(2)) Payment 
    FROM dbo.table1 
) AS T
) AS EC(ExpCalc)

加入后我需要这样的东西：

CROSS APPLY(
SELECT SUM(Payment)
FROM (
    SELECT TOP(ABS(2)) Payment 
    FROM dbo.table1 t1
) AS T
) AS EC(ExpCalc) JOIN dbo.info i on t1.key = i.key 

我怎样才能做到这一点？

Answer 1

首先，你不能做你想做的事，因为你没有返回key。但更大的答案是您可以执行join，但您可以将其作为相关子查询：

CROSS APPLY
(SELECT SUM(Payment)
 FROM (SELECT TOP(ABS(2)) Payment 
       FROM dbo.table1 t1
       WHERE t1.key = i.key
------^
      ) T
) AS EC(ExpCalc) 

这将出现在FROM 子句中，如下所示：

FROM dbo.info i CROSS APPLY
(SELECT SUM(Payment)
 FROM (SELECT TOP(ABS(2)) Payment 
       FROM dbo.table1 t1
       WHERE t1.key = i.key
      ) T
) AS EC(ExpCalc)