如何将公用表表达式的结果集与sql server 2005中的其他现有表连接起来？答案

【问题标题】：How to join the result set of Common Table Expression with other existing table in sql server 2005?如何将公用表表达式的结果集与sql server 2005中的其他现有表连接起来？
【发布时间】：2010-11-15 09:42:51
【问题描述】：

我想将公用表表达式的结果集与现有表连接起来。使用以下查询中给出的 group by 子句会出现问题。谁能告诉我如何加入这两个表？

With CTEQuery
as
(SELECT     StudentOnlineExamCourseAnswer.StudentID, StudentOnlineExamCourseAnswer.OnlineExamID, StudentOnlineExamCourseAnswer.CourseID, 
                      StudentOnlineExamCourseAnswer.CentreID,
case QuestionBank.ComplexLevelID when 1 then (2) when 2 then (4) when 3 then (6) when 4 then (8) when 5 then (10) end as Mark
FROM         QuestionBank INNER JOIN
                      StudentOnlineExamCourseAnswer ON QuestionBank.Answer = StudentOnlineExamCourseAnswer.Answer AND 
                      QuestionBank.QuestionID = StudentOnlineExamCourseAnswer.QuestionID) 
select StudentID, OnlineExamID ,CourseID , CentreID , sum(Mark) as 'Total Marks' from CTEQuery 
group by StudentID, OnlineExamID ,CourseID , CentreID

【问题讨论】：

标签： sql-server common-table-expression

【解决方案1】：

您可以为单个选择定义多个 CTE，每个 CTE 都可以引用之前定义的 CTE。所以你可以这样做：

With CTEQuery
as
(SELECT     StudentOnlineExamCourseAnswer.StudentID, StudentOnlineExamCourseAnswer.OnlineExamID, StudentOnlineExamCourseAnswer.CourseID, 
                      StudentOnlineExamCourseAnswer.CentreID,
case QuestionBank.ComplexLevelID when 1 then (2) when 2 then (4) when 3 then (6) when 4 then (8) when 5 then (10) end as Mark
FROM         QuestionBank INNER JOIN
                      StudentOnlineExamCourseAnswer ON QuestionBank.Answer = StudentOnlineExamCourseAnswer.Answer AND 
                      QuestionBank.QuestionID = StudentOnlineExamCourseAnswer.QuestionID)
, SummarizedCTE as ( 
select StudentID, OnlineExamID ,CourseID , CentreID , sum(Mark) as TotalMark from CTEQuery 
group by StudentID, OnlineExamID ,CourseID , CentreID)
select <new query involving joining SummarizedCTE with the "other table" referenced in your discussion>

【讨论】：

【解决方案2】：

您需要先创建您的 CTE，然后在下一个 SELECT 语句中使用它。

WITH cteTest (Column1) AS 
(
    SELECT column1
      FROM table1
)

SELECT *
  FROM cteTest
  JOIN Table2
    ON cteTest.column1 = Table2.column1

【讨论】：

【解决方案3】：

例子

with demoCTE 
as
(
  select id from table1
) select * from demoCTE
    join table2
   on demoCTE.id= table2.id

【讨论】：