SQL group by 子句错误子查询返回超过 1 个值。当子查询跟在 =、!=、

Question

我有一个查询，它按组计算活跃客户，并且必须按组计算取货量。

SELECT  [Category] = ISNULL(c.Category, 'Total'),
        COUNT (hs.ClientID) as '3 Mo Clients',
        (COUNT (hs.ClientID))/3 as MoAVG
      ,(select COUNT(PickupID)from Pickup where PickupDate between '2013-01-01' and '2013-03-30' group by CategCode) as '3 Mo Picups'

FROM    Category c 
        LEFT JOIN history hs
            ON hs.CategCode = c.CategCode 
            where ReccordDate between '2013-01-01' and '2013-03-30'
GROUP BY Category
WITH ROLLUP

此查询抛出错误：Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

如果我没有在 4 行中使用 group by，它可以工作，但不会按组划分拾音器。 这是代码的 4 行中没有 group by 子句的示例如何工作

任何想法如何解决它？

Answer 1

尝试添加这个条件：CategCode = c.CategCode

SELECT [Category] = ISNULL(c.Category, 'Total'),
       COUNT (hs.ClientID) as [3 Mo Clients],
       (COUNT (hs.ClientID))/3 as MoAVG
      ,(SELECT COUNT(PickupID) 
        FROM Pickup 
        WHERE PickupDate between '2013-01-01' and '2013-03-30'
          AND  CategCode = c.CategCode
       ) AS [3 Mo Picups]
FROM Category c LEFT JOIN history hs ON hs.CategCode = c.CategCode 
WHERE ReccordDate between '2013-01-01' and '2013-03-30'
GROUP BY c.CategCode, c.Category 
WITH ROLLUP

或

SELECT [Category] = ISNULL(c.Category, 'Total'),
       COUNT (hs.ClientID) as [3 Mo Clients],
       (COUNT (hs.ClientID))/3 as MoAVG,
       SUM(o.cnt) AS [3 Mo Picups]
FROM Category c LEFT JOIN history hs ON hs.CategCode = c.CategCode
                CROSS APPLY (
                             SELECT COUNT(PickupID) AS cnt
                             FROM Pickup 
                             WHERE PickupDate between '2013-01-01' and '2013-03-30'
                               AND  CategCode = c.CategCode
                             ) o
WHERE ReccordDate between '2013-01-01' and '2013-03-30'
GROUP BY c.Category 
WITH ROLLUP