获取单行而不是两行数据 SQL

Question

我有 sql ;

select 
Program,
CASE WHEN ClassMissed = 0 THEN COUNT(ClassMissed) ELSE 0 END as Completed,
CASE WHEN ClassMissed = 1 THEN COUNT(ClassMissed) ELSE 0 END as One_Days_Missed,
CASE WHEN ClassMissed = 2 THEN COUNT(ClassMissed) ELSE 0 END as Two_Days_Missed,
CASE WHEN ClassMissed = 3 THEN COUNT(ClassMissed) ELSE 0 ENd as Three_Days_Missed
from
#temp
group by Program,ClassMissed

下面给出了我的输出：

Program | Completed | One_Days_Missed | Two_Days_Missed |Three_Days_Missed
________________________________________________________________________________
Prog1   | 0       |      19   |      0     |       0 
Prog1 |       0       |      0   |      0     |       2

但我预计会低于 table

Program | Completed | One_Days_Missed | Two_Days_Missed |Three_Days_Missed
________________________________________________________________________________
Prog1   | 0       |      19   |      0     |       2

我必须按 Classmissed 分组才能 运行 查询。

请给我更好的解决方案？

谢谢

Answer 1

你应该使用 SUM(CASE WHEN..END).

CREATE TABLE #Temp(
    Program     VARCHAR(20),
    ClassMissed INT
)
INSERT INTO #Temp VALUES
('Prog1', 1), ('Prog1', 1), ('Prog1', 1),
('Prog1', 1), ('Prog1', 1), ('Prog1', 1),
('Prog1', 1), ('Prog1', 1), ('Prog1', 1),
('Prog1', 1), ('Prog1', 1), ('Prog1', 1),
('Prog1', 1), ('Prog1', 1), ('Prog1', 1),
('Prog1', 1), ('Prog1', 1), ('Prog1', 3),
('Prog1', 1), ('Prog1', 1), ('Prog1', 3);

SELECT 
    Program,
    SUM(CASE WHEN ClassMissed = 0 THEN 1 ELSE 0 END) AS Completed,
    SUM(CASE WHEN ClassMissed = 1 THEN 1 ELSE 0 END) AS One_Days_Missed,
    SUM(CASE WHEN ClassMissed = 2 THEN 1 ELSE 0 END) AS Two_Days_Missed,
    SUM(CASE WHEN ClassMissed = 3 THEN 1 ELSE 0 END) AS Three_Days_Missed
FROM #Temp
GROUP BY Program

DROP TABLE #Temp

结果

Program              Completed   One_Days_Missed Two_Days_Missed Three_Days_Missed
-------------------- ----------- --------------- --------------- -----------------
Prog1                0           19              0               2