Question

我正在尝试查询表并将结果转换为变量。使用变量结果，使用变量详细信息作为过滤器，执行另一个选择查询。

到目前为止：

DECLARE @storeIds int    
SET @storeIds = (SELECT StoreID FROM Store WHERE ParentStoreID=9)

--print @storeIds

SELECT c.FirstName, c.LastName, c.CustomerId, r.StoreID
FROM Consumer AS c
    INNER JOIN Purchases AS r ON c.CustomerId= r.CustomerId
WHERE r.StoreID = @storeIds
   -- (r.StoreID = 9) OR
   -- (r.StoreID = 10) OR
   -- (r.StoreID = 11)
GROUP BY c.FirstName, c.LastName, c.CustomerId, r.StoreID
ORDER BY c.FirstName

我收到错误消息：

子查询返回的值超过1。当子查询遵循=，！=，＆lt;，＆lt; =，＆gt;，＆gt; =或子查询用作表达式时，不允许这样做。

Answer 1

除非您特别想在其他地方使用@StoreIds变量，否则您只需将WHERE条款修改为：

WHERE r.StoreID IN (SELECT StoreID FROM Store WHERE ParentStoreID = 9)

Answer 2

您的问题是多个商店具有相同的ParentStoreID，因此在您查询时，您尝试将多个值添加到INT变量中。

你可以看一下尝试：

SELECT c.FirstName, c.LastName, c.CustomerId, p.StoreID
FROM Consumer AS c
INNER JOIN Purchases AS p ON c.CustomerId = p.CustomerId
INNER JOIN Store AS s ON p.StoreId = s.StoreId
WHERE s.ParentStoreID = 9
GROUP BY c.FirstName, c.LastName, c.CustomerId, r.StoreID
ORDER BY c.FirstName

此查询应该为您提供所需的所有商品，来自ParentStoreId = 9的所有商店。

有关JOINS的信息也可能对您有所帮助。

Answer 3

Barry和Adam Wenger拥有最佳方法，但要直接解决错误，您可以确保在使用top 1修饰符设置变量时获得一个结果。像：

DECLARE @storeIds int     
SET @storeIds = (SELECT top 1 StoreID FROM Store WHERE ParentStoreID=9)

Answer 4

可以用不同的方式完成：

使用子查询

SELECT c.FirstName, c.LastName, c.CustomerId, r.StoreID
FROM Consumer AS c
   INNER JOIN Purchases AS r ON c.CustomerId= r.CustomerId
WHERE r.StoreID = (SELECT StoreID FROM Store WHERE ParentStoreID=9)
GROUP BY c.FirstName, c.LastName, c.CustomerId, r.StoreID
ORDER BY c.FirstName

使用加入操作

SELECT c.FirstName, c.LastName, c.CustomerId, r.StoreID
FROM Consumer AS c
    INNER JOIN Purchases AS r ON c.CustomerId= r.CustomerId 
    INNER JOIN (SELECT StoreID FROM Store WHERE ParentStoreID=9) AS s(StoreID)
        ON r.StoreID = s.StoreID
GROUP BY c.FirstName, c.LastName, c.CustomerId, r.StoreID
ORDER BY c.FirstName

创建一个sql变量并查询其他表

4 个答案: