使用 Table2 条件中的 Table1 列值将 Table1 与 Table2 连接起来答案

【问题标题】：Join Table1 with Table2 using Table1 column values in Table2's conditionals使用 Table2 条件中的 Table1 列值将 Table1 与 Table2 连接起来
【发布时间】：2011-09-14 19:44:24
【问题描述】：

我有以下选择语句...

SELECT ROW_NUMBER() OVER(order by cola) as [id], cola
  FROM Table1

这构成了我想要作为@var 插入的所有值的表，现在它可以工作，但我每次都必须指定@var...

 SELECT @var AS [Cola], (

            SELECT COUNT(*)
              FROM vwTableA AS Z
             WHERE Cola = COALESCE(@var,Cola)
               AND NOT EXISTS (

                        SELECT * 
                          FROM TableB
                         WHERE Colb = Z.Colb

                              )

  ) AS [NewCol1],
  (

            SELECT COUNT(*)
              FROM vwTableB AS Y
             INNER JOIN TableC AS C
                ON Y.Colc = C.Colc
             WHERE Y.Cola = @var

  ) AS [NewCol2],
  (

            SELECT COUNT(*)
              FROM vwTableC AS X
             INNER JOIN TableD AS D
                ON X.Colc = D.Colc
             WHERE X.Cola = @var

  ) AS [NewCol3]

所以我想通过我显示的第一个 Select/Table 中的所有“cola”值运行第二个选择，而不是必须指定 @var 并且每次只返回一行。我怎样才能做到这一点？

【问题讨论】：

标签： sql select join where

【解决方案1】：

如果您使用公用表表达式 CTE，您可以使用它来加入您的其他语句

with var as 
( SELECT ROW_NUMBER() OVER(order by cola) as [id], cola
  FROM Table1)


SELECT var.id  AS [Cola], (

            SELECT COUNT(*)
              FROM vwTableA AS Z
             WHERE Cola = COALESCE(var.id,Cola)
               AND NOT EXISTS (

                        SELECT * 
                          FROM TableB
                         WHERE Colb = Z.Colb

                              )

  ) AS [NewCol1],
  (

            SELECT COUNT(*)
              FROM vwTableB AS Y
             INNER JOIN TableC AS C
                ON Y.Colc = C.Colc
             WHERE Y.Cola = var.id

  ) AS [NewCol2],
  (

            SELECT COUNT(*)
              FROM vwTableC AS X
             INNER JOIN TableD AS D
                ON X.Colc = D.Colc
             WHERE X.Cola = var.id

  ) AS [NewCol3]
FROM var

【讨论】：