Question

我有3个SELECT语句，我想组合成一个：

SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname 
FROM feedbacks A 
    INNER JOIN users B 
         ON A.userid = B.userid 
WHERE DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
GROUP BY fullname

SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname 
FROM feedbacks A 
    INNER JOIN users B 
        ON A.userid = B.userid 
WHERE status = 'C' 
AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
GROUP BY fullname`

SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname 
FROM feedbacks A 
    INNER JOIN users B ON A.userid = B.userid 
WHERE caused_change = 1 
AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
GROUP BY fullname

但是将它们组合似乎总是会返回错误:(操作数应该包含1列）

SELECT 
(SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname) AS T1,  
(SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE status = 'C' AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname) AS T2,  
(SELECT COUNT(A.id), CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE caused_change = 1 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname) AS T3

所以我尝试从各个语句中删除JOIN和GROUP来制作：

SELECT CONCAT(B.fname, ' ', B.lname) AS fullname,
(SELECT COUNT(A.id) FROM feedbacks A WHERE DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11') AS T1,  
(SELECT COUNT(A.id) FROM feedbacks A WHERE status = 'C' AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11') AS T2,
(SELECT COUNT(A.id) FROM feedbacks A WHERE caused_change = 1 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11') AS T3
FROM feedbacks 
    INNER JOIN users B 
        ON feedbacks.userid = B.userid 
GROUP BY fullname

但是这会返回所有内容的总数而不是用户分解（因为计数在where子句中没有说明有关userid或fullname的内容，毫无疑问）。

我觉得我很亲密，但却缺少一些东西。谁能指出我在这里的正确方向？我只是想了解我做错了什么。

感谢您的时间。

Answer 1

最好的方法是使用条件SUM：

SELECT CONCAT(B.fname, ' ', B.lname) AS fullname,
       SUM(
           CASE WHEN DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
           THEN 1 ELSE 0 END
       ) AS T1,
       SUM(
           CASE WHEN status = 'C' 
                 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
           THEN 1 ELSE 0 END
       ) AS T2,
       SUM(
           CASE WHEN caused_change = 1 
                 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' 
           THEN 1 ELSE 0 END
       ) AS T3
FROM feedbacks 
    INNER JOIN users B 
        ON feedbacks.userid = B.userid 
GROUP BY fullname

Answer 2

我不知道您是否可以将这3个查询合并为一个统一查询。你有3'的子句重叠：

第一个查询：属于日期范围的所有记录
第二个查询：属于日期范围但状态='C'的所有记录第三个查询：属于日期范围的所有记录，但也包含cause_change = 1

在逻辑上，第一个查询已包含第二个和第三个查询中的所有记录，因此您需要重复计算＃2和＃3的结果。

但是，如果您确实希望将所有三个结合到一个结果中，那么请执行外部查询方法：

SELECT sum(cnt), fullname
FROM (
    SELECT COUNT(A.id) as cnt, CONCAT(B.fname,' ', B.lname) AS fullname
    FROM feedbacks A
    INNER JOIN users B ON A.userid = B.userid
    WHERE DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11'
    GROUP BY fullname

    UNION

    ...
    WHERE status = 'C' AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11'

    UNION

    ...
    WHERE caused_change = 1 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11'
) AS innerquery
GROUP BY fullname

请注意第一个内部查询中count()上的别名。这是为了使计数字段显示为外部查询的“cnt”。

Answer 3

UNION和SUM应该做的工作。您的代码应如下所示：

 select sum(x.col1), x.fullname
from
(SELECT COUNT(A.id)as col1, CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname
UNION
SELECT COUNT(A.id)as col1, CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE status = 'C' AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname
UNION
SELECT COUNT(A.id)as col1, CONCAT(B.fname,' ', B.lname) AS fullname FROM feedbacks A INNER JOIN users B ON A.userid = B.userid WHERE caused_change = 1 AND DATE(origindate) BETWEEN '2011-03-01' AND '2011-07-11' GROUP BY fullname
)x
group by x.fullname

将多个计数组合成一个查询 - group by

3 个答案: