是否有可能建立我的查询只有一个选择语句？

Question

下面是我的查询和它的输出。是否有可能建立我的查询只有一个选择语句（我有两个在我的查询）？它用于性能目的。

WITH GradePassFail AS (
    SELECT 
     Subject, 
     Grade, 
     CASE WHEN Grade >= 50 THEN 1 ELSE 0 END AS Pass, 
     CASE WHEN Grade < 50 THEN 1 ELSE 0 END AS Fail 
    FROM Grade_report 
) 
SELECT Subject, MAX(Grade) AS Grade, SUM(Pass) AS Pass, SUM(Fail) AS Fail 
FROM GradePassFail 
GROUP BY Subject 

Answer 1

您可以将SUM函数中执行CASE报表合格/不合格......那么你不需要CTE：

SELECT 
    Subject, 
    MAX(Grade) Grade, 
    SUM(CASE WHEN Grade >= 50 THEN 1 ELSE 0 END) AS Pass, 
    SUM(CASE WHEN Grade < 50 THEN 1 ELSE 0 END) AS Fail 
FROM 
    Grade_report 
GROUP BY Subject 

您可以验证此：

http://sqlfiddle.com/#!3/99cd4/7