Question

我想合并一个表中的两个SQL选择

查询1：

SELECT UserId
FROM ShoppingLike
WHERE (ShoppingScoreTypeId = 2) AND (WhichId = 75)

查询2：

SELECT ShoppingLike.WhichId
FROM ShoppingLike
WHERE (ShoppingLike.ShoppingScoreTypeId = 2) AND (ShoppingLike.UserId = 189)

而不是查询1中的75，我应该如何使用查询2的结果？

Answer 1

SELECT        UserId
FROM            ShoppingLike
WHERE        (ShoppingScoreTypeId = 2)
AND WhichId = (
 SELECT        top 1 ShoppingLike.WhichId
 FROM            ShoppingLike
 WHERE        (ShoppingLike.ShoppingScoreTypeId = 2) AND (ShoppingLike.UserId = 189)
)

Answer 2

可能有子选择查询吗？

SELECT UserId
FROM ShoppingLike
WHERE WhichId IN (
    SELECT WhichId
    FROM ShoppingLike
    WHERE (ShoppingScoreTypeId = 2) AND (UserId = 189)
)

虽然这总会产生UserId 189行，但在这种情况下，查询可以简单地写成：

SELECT UserId
FROM ShoppingLike
WHERE (ShoppingScoreTypeId = 2) AND (UserId = 189)

这会为ShoppingScoreTypeId = 2的UserId = 2的每条记录返回一行。

如何合并两个sql选择

2 个答案: