Question

表CMC

ID CMD USERID STATUS
1  94    4     1
2  102  24     1
3  36   32     1
4  44   40     1
5  82   2      1 
6  66   27     1
7  94   56     1
8  102   2     1

表CCC

ID COURSEID CMD 
1     2     94     
2    16     102
3    8      82
4    5      94
5    4      66  
6    8      36
7    2      56
8    19     44-

表CMD

ID  COURSEID
44    5    
66    3   
102   16   
82    5   
94    8  
56    4   
66    2   
36    19

Iam尝试使用状态计算创建一个sql查询：

COUNT(CMC.USERID)  COURSED  COMPLETED  INPROCESS  NOTSTARTED

已完成：如果该特定课程的COUNT（CMC）== COUNT（CCC）

INPROCESS：如果COUNT（CMC）> 0，但不等于COUNT（CCC）

NOTSTARTED：如果COUNT（CMC）= 0

有人建议我使用以下查询：

SELECT count(cmc.userid),

(SELECT count(ccc.id) FROM ccc HAVING count(cmc.userid) =  count(ccc.id) ) AS "completed"
(SELECT count(ccc.id) FROM ccc HAVING count(cmc.userid) >0  AND count(ccc.id) !== count(cmc.userid) ) AS "Inprocess"
(SELECT count(ccc.id) FROM ccc HAVING count(cmc.userid) =  0 ) AS "Notstarted"

FROM 
cmc 
WHERE status = 1

Answer 1

我通常更喜欢在子选择语句中执行摘要。然后我可以更轻松地排除故障。这是完成的查询（如果我理解你的问题）：

SELECT UserId, 
    CASE WHEN CMCount=CCCount THEN 1 ELSE 0 END AS Completed, 
    CASE WHEN CMCount>0 and CMCount<>CCCount THEN 1 ELSE 0 END AS InProcess,
    CASE WHEN CMCount=0 THEN 1 ELSE 0 END AS NotStarted
FROM (
    SELECT CMC.USERID AS UserId, COUNT(CMC.CMD) AS CMCount, COUNT(CCC.CMD) AS CCCount
    FROM CMC LEFT JOIN CCC ON CMC.CMD=CCC.CMD
    GROUP BY CMC.USERID
    ) AS Summary

SQL计数计算

1 个答案: