不了解查询行为

Question

我在报表生成器中有一个奇怪的行为。 在尝试使用报表生成器之前，我正在使用现有数据集并在 SQL Studio 中测试我自己的代码。我迷路了，因为我不明白为什么以下不起作用：

    SELECT
        v_Collection_Alias.Name as CollectionName,  
        v_Package_Alias.Name as SoftwareName, 
        'Package' as ApplicationType,
        NumberSuccessTable='NumberSuccessTable', sum(case when stat.LastState in (-1,13) then 1 else 0 end) as NumberSuccess,
        NumberInProgressTable='NumberInProgress', sum(case when stat.LastState in (8,9) then 1 else 0 end) as NumberInProgress,
        NumberUnknownTable='NumberUnknown', sum(case when stat.LastState in (0) then 1 else 0 end) as Unknown,
        NumberErrorTable='NumberError', sum(case when stat.LastState in (11) then 1 else 0 end) as NumberError,
        NumberOtherTable='NumberOther', sum(case when stat.LastState in (10) then 1 else 0 end) as NumberOther,
        '' as LastModifiedby,
        '' as Version,
        v_Advertisement_Alias.CollectionID as CollectionID,
        v_Advertisement_Alias.AdvertisementID as DeploymentID,
        '' as CI_ID,
        '' as DeploymentTime,
        v_Advertisement_Alias.PresentTime as ModificationTime,
        '' as AssignmentID

FROM fn_rbac_Advertisement(@UserSIDs) v_Advertisement_Alias  
JOIN fn_rbac_ClientAdvertisementStatus(@UserSIDs)  stat on v_Advertisement_Alias.AdvertisementID = stat.AdvertisementID
INNER JOIN fn_rbac_Package2(@UserSIDs) v_Package_Alias ON v_Advertisement_Alias.PackageID = v_Package_Alias.PackageID 
INNER JOIN fn_rbac_Collection(@UserSIDs) v_Collection_Alias ON v_Advertisement_Alias.CollectionID = v_Collection_Alias.CollectionID

报告生成器中的这个提示我一个错误，因为fn_rbac_Advertisement.Name 需要一个 group by 子句。鉴于以下内容在原始报告中正常工作：

    SELECT
    v_Collection_Alias.Name as CollectionName,  
    v_Package_Alias.Name as SoftwareName, 
    '' as ApplicationType,
    '' as NumberSuccess,
    '' as NumberInProgress,
    '' as NumberUnknown,
        '' as NumberErrors,
        '' as NumberOther,
    '' as LastModifiedby,
    '' as Version,
    v_Advertisement_Alias.CollectionID as CollectionID,
    v_Advertisement_Alias.AdvertisementID as DeploymentID,
    '' as CI_ID,
    '' as DeploymentTime,
    v_Advertisement_Alias.PresentTime as ModificationTime,
    '' as AssignmentID,
    '' as ApplicationType 


FROM fn_rbac_Advertisement(@UserSIDs) v_Advertisement_Alias  
INNER JOIN fn_rbac_Package2(@UserSIDs) v_Package_Alias ON v_Advertisement_Alias.PackageID = v_Package_Alias.PackageID 
INNER JOIN fn_rbac_Collection(@UserSIDs) v_Collection_Alias ON v_Advertisement_Alias.CollectionID = v_Collection_Alias.CollectionID

以下内容返回了我在 SQL Studio 中想要的内容：

Select 
NumberSuccessTable='NumberSuccessTable', sum(case when stat.LastState in (-1,13) then 1 else 0 end),
NumberInProgressTable='NumberInProgress',  sum(case when stat.LastState in (8,9) then 1 else 0 end),
NumberUnknownTable='NumberUnknown',  sum(case when stat.LastState in (0) then 1 else 0 end) AS NumberU,
NumberErrorTable='NumberError',  sum(case when stat.LastState in (11) then 1 else 0 end) AS NumberError,
NumberOtherTable='NumberOther', sum(case when stat.LastState in (10) then 1 else 0 end) as NumberOther
From  v_ClientAdvertisementStatus stat

感谢大家的帮助！ :)

Answer 1

第一个查询：

当您使用像 SUM 这样的聚合函数时，您需要对所有没有聚合函数的列进行 GROUP BY。

第二次查询：

这很有效，因为您的选择中没有聚合函数，因此您不必使用 GROUP BY 并且报表生成器可以为您处理总和和分组依据。

第三次查询：

此查询有效，因为您在所有列上都有聚合函数，因此您不需要 GROUP BY。

永远记住LOGICAL查询处理顺序如下：

1.来自 2.在哪里 3.分组依据 4.拥有 5.选择 6.订购方式

因此，您的 GROUP BY 发生在 SELECT 之前，因此当您 group by 时，您不能在 group by 子句中包含 ''，因为该列尚不存在。 所以它会给你一个错误。

Answer 2

使用聚合函数（例如 SUM）时，您必须将 GROUP BY 子句应用于所有未聚合的列，例如：

GROUP BY v_Collection_Alias.Name,  
    v_Package_Alias.Name, 
    v_Advertisement_Alias.CollectionID as CollectionID,
    v_Advertisement_Alias.AdvertisementID as DeploymentID,
    v_Advertisement_Alias.PresentTime as ModificationTime

或者，如果您不想维护冗长的 GROUP BY 子句，您可以从 SELECT 语句中删除 SUM 函数并让报表处理聚合，并在报表生成器中进行适当的分组。