sql - 如何重用公共(public)表表达式

Question

我正在使用通用表表达式进行分页:

with query as (
  Select Row_Number() over (Order By OrderNum ASC) as TableRowNum,
         FirstName,
         LastName
  From   Users
)
Select * from query where TableRowNum between 1 and 25 Order By TableRowNum ASC

在进行此查询后，我立即进行几乎相同的查询以检索项目总数:

with query as (
  Select Row_Number() over (Order By OrderNum ASC) as TableRowNum,
         FirstName,
         LastName
  From   Users
)
Select Count(*) from query

我尝试将它们组合在一起(即:定义 CTE，查询数据，然后查询计数，但是当我这样做时，我收到一条错误消息“无效的对象名称'查询'”来响应第二个查询(伯爵)。

有没有办法将这两个查询合并为一个，以节省与数据库的往返？

Answer 1

如果您在两个不同的查询中不需要它们，您可以尝试

;with query as (
  Select Row_Number() over (Order By UserID ASC) as TableRowNum,
         FirstName,
         LastName
  From   Users
),
totalCount AS (
    SELECT COUNT(1) Total FROM query
)
Select  query.*,
        Total
from    query, totalCount 
where   TableRowNum 
between 1 and 25 
Order By TableRowNum ASC

如果您确实需要 2 个不同的查询，请使用表变量

DECLARE @User TABLE(
        TableRowNum INT,
        FirstName VARCHAR(50),
        LastName VARCHAR(50)
)
;with query as (
  Select Row_Number() over (Order By UserID ASC) as TableRowNum,
         FirstName,
         LastName
  From   Users
)
INSERT INTO @User
SELECT  TableRowNum,
        FirstName,
        LastName
FROM    query

SELECT  *
FROM    @User
where   TableRowNum 
between 1 and 25 
Order By TableRowNum ASC

SELECT COUNT(1) FROM @User