Question

我有一个查询，使用公用表表达式检索页面的所有模块和子模块。是否可以多次使用cte的结果？

例如

WITH top_level_modules (
[AppContentModuleID]
,[SortIndex]
,[ContentHolderName]
,[OwnerType]
,[AppContentModuleGuid]
,[parent_AppContentModuleID]
,[ModuleID]
,[RenderIDTag]
,[WrapperType]
,[Level]
)
AS
( 
SELECT amcp.[AppContentModuleID]
    ,amcp.[SortIndex]
    ,amcp.[ContentHolderName]
    ,1
    ,amc.[AppContentModuleGuid]
    ,amc.[parent_AppContentModuleID]
    ,amc.[ModuleID]
    ,amc.[RenderIDTag]
    ,amc.[WrapperType]
    ,0 AS [Level]
FROM [dbo].[application_module_content_page] amcp
INNER JOIN [dbo].[application_module_content] amc on amcp.[AppContentModuleID] = amc.[AppContentModuleID]
WHERE amcp.[PageID] = @PageID
UNION
SELECT amcm.[AppContentModuleID]
    ,amcm.[SortIndex]
    ,amcm.[ContentHolderName]
    ,2
    ,amc.[AppContentModuleGuid]
    ,amc.[parent_AppContentModuleID]
    ,amc.[ModuleID]
    ,amc.[RenderIDTag]
    ,amc.[WrapperType]
    ,0
FROM [dbo].[application_module_content_masterpage] amcm
INNER JOIN [dbo].[application_module_content] amc on amcm.[AppContentModuleID] = amc.[AppContentModuleID]
WHERE amcm.[AppMasterPageID] = @MasterPageID
),
child_modules AS 
(
SELECT tlm.[AppContentModuleID]
    ,tlm.[SortIndex]
    ,tlm.[ContentHolderName]
    ,tlm.[OwnerType]
    ,tlm.[AppContentModuleGuid]
    ,tlm.[parent_AppContentModuleID]
    ,tlm.[ModuleID]
    ,tlm.[RenderIDTag]
    ,tlm.[WrapperType]
    ,tlm.[Level]
FROM top_level_modules tlm
UNION ALL
SELECT 
    amc.[AppContentModuleID]
    ,CASE WHEN amc.[SortIndex] IS NULL THEN tlm.[SortIndex] ELSE amc.[SortIndex] END
    ,null
    ,3
    ,amc.[AppContentModuleGuid]
    ,amc.[parent_AppContentModuleID]
    ,amc.[ModuleID]
    ,amc.[RenderIDTag]
    ,amc.[WrapperType]
    ,[Level] + 1 AS [Level]
FROM [dbo].[application_module_content] amc
INNER JOIN child_modules tlm on tlm.[AppContentModuleID] = amc.[parent_AppContentModuleID]
)
SELECT * 
FROM child_modules cm
ORDER BY cm.[OwnerType]
, cm.[Level]
, cm.[SortIndex]

SELECT apcs.[StyleType] 
    ,apcs.[StyleName]
    ,apcs.[StyleValue]
FROM child_modules cm
INNER JOIN dbo.[application_module_content_style] apcs 
on cm.AppContentMdouleID = apcs.AppContentMdouleID

第一个选择有效，但第二个选择会引发错误“无效对象名称'child_modules'。”

Answer 1

来自the WITH common_table_expression manual：

指定临时命名结果集，称为公用表表达式（CTE）。这是从一个简单的查询和在单个 SELECT，INSERT，UPDATE或DELETE语句的执行范围内定义的。

所以，不，你不能将CTE的范围扩展到它定义的SELECT语句之外。如果你想要将结果存储在临时表中，那么你必须将结果存储在临时表或表值变量中一次。

Answer 2

您需要将child_modules CTE拆分为两个CTE。

第一个包含当前child_modules CTE的第一个SELECT，然后使用第二个基于child_modules的CTE。

然后，您的最终SELECT将使用第三个CTE而不是child_modules。

Answer 3

使用如下：

Create FUNCTION [dbo].[fnGetAllData] 
(
    @UserId int    
)
RETURNS TABLE
AS
RETURN  
(
    WITH UserPRecursive AS
    (   
    SELECT u.userid,u.OverrideID
    FROM UserOverride u where OverrideID=@UserId
    UNION ALL
    SELECT C.userid,C.OverrideID
    FROM UserOverride AS C INNER JOIN UserPRecursive AS cr
    ON C.OverrideID = cr.userid 
    )   
    , UserCRecursive AS
    (   
    SELECT u.userid,u.OverrideID
    FROM UserOverride u where UserID=@UserId
    UNION ALL
    SELECT C.userid,C.OverrideID
    FROM UserOverride AS C INNER JOIN UserCRecursive AS cr
    ON C.userid = cr.OverrideID 
    )
    SELECT distinct CR1.userid as userId FROM UserPRecursive AS CR1
    UNION ALL
    SELECT distinct cr2.OverrideID as userId FROM UserCRecursive AS CR2 
    UNION ALL
    select userid from [User] where UserID=@UserId
)

重用SQL Server公用表表达式的结果

3 个答案: