Question

我不想创建一个像这样构建的视图：（简化的）

Create VIEW viewAll AS
With TempLevel1 AS

（ SELECT statement ）

With TempLevel2 AS (SELECT * from TempLevel1)

SELECT * from TempLevel2

问题是因为我不能使用这样的With语句以下错误：

关键字附近的语法错误＆＃39;使用＆＃39;。   关键字＆＃39;附近的语法不正确，用＆＃39;。

如果这个陈述是   公用表表达式，xmlnamespaces子句或更改跟踪   context子句，前一个语句必须以a结尾   分号。

我必须指定SELECT查询更复杂，我必须使用两次。

更好的做法是将第一个with语句创建为另一个视图，如viewTempLevel1（并在With TempLevel2语句中使用它）？

Answer 1

从公共表格表达式的documentation（ CTE ），您可以

使用逗号分隔多个CTE定义

示例（直接取自文档）

WITH Sales_CTE (SalesPersonID, TotalSales, SalesYear)  
AS  
-- Define the first CTE query.  
(  
    SELECT SalesPersonID, SUM(TotalDue) AS TotalSales, YEAR(OrderDate) AS SalesYear  
    FROM Sales.SalesOrderHeader  
    WHERE SalesPersonID IS NOT NULL  
       GROUP BY SalesPersonID, YEAR(OrderDate)  

)  
,   -- Use a comma to separate multiple CTE definitions.  

-- Define the second CTE query, which returns sales quota data by year for each sales person.  
Sales_Quota_CTE (BusinessEntityID, SalesQuota, SalesQuotaYear)  
AS  
(  
       SELECT BusinessEntityID, SUM(SalesQuota)AS SalesQuota, YEAR(QuotaDate) AS SalesQuotaYear  
       FROM Sales.SalesPersonQuotaHistory  
       GROUP BY BusinessEntityID, YEAR(QuotaDate)  
)  

-- Define the outer query by referencing columns from both CTEs.  
SELECT SalesPersonID...

在您的情况下，语法将是......

With TempLevel1 AS
    ( SELECT statement [...]), 
TempLevel2 AS 
    (SELECT * from TempLevel1)

SELECT * from TempLevel2

Answer 2

您不需要重复WITH关键字。用逗号分隔CTE表达式：

With CTE_Level1 AS
( 
    SELECT statement 
),
CTE_Level2 AS 
(
    SELECT * from CTE_Level1
)
SELECT * from CTE_Level2

不能两次使用WITH语句

2 个答案: