Question

我有查询

SELECT p. * , COUNT( r.poll_option_id ) AS voteCount
FROM poll_options AS p
LEFT JOIN poll_responses AS r ON ( r.poll_option_id = p.id ) 
WHERE p.poll_id =1
GROUP BY p.id
LIMIT 0 , 30

它返回我正确的数据

 id poll_id caption voteCount   
 1  1   32  1
 2  1   256 1
 3  1   512 0

现在我需要计算别名voteCount，所以对于这个例子，它将是1 + 1 + 0 = 2 ..并将其作为另一个别名返回。我怎么能这样做？我必须只使用1个查询，而且我没有编辑数据库的权限。我试过一些例子 MySQL Join two tables count and sum from second table MySQL query, COUNT and SUM with two joined tables 还有更多但没有运气..

Answer 1

围绕它换行另一个查询？

SELECT id, poll_id, SUM(voteCount) AS votecount
FROM ( ... your query here ... ) As subquery
GROUP BY poll_id

Answer 2

您可以通过计数列的计算总和

使用交叉联接到同一查询

SELECT t1.*,t2.totalvoteCount FROM (
SELECT p. * , COUNT( r.poll_option_id ) AS voteCount
FROM poll_options AS p
LEFT JOIN poll_responses AS r ON ( r.poll_option_id = p.id ) 
WHERE p.poll_id =1
GROUP BY p.id
LIMIT 0 , 30
) t1
CROSS JOIN (
SELECT SUM(voteCount) totalvoteCount
FROM (
SELECT  p.id,COUNT( r.poll_option_id ) AS voteCount
FROM poll_options AS p
LEFT JOIN poll_responses AS r ON ( r.poll_option_id = p.id ) 
WHERE p.poll_id =1
GROUP BY p.id
LIMIT 0 , 30
) t
) t2

输出如下

id poll_id caption voteCount   totalvoteCount 
 1  1       32          1        2
 2  1       256         1        2
 3  1       512         0        2

Answer 3

在您的示例中，voteCount表示每个组的计数。如果您希望所有组中的计数，那么您可以省略group by子句（如果您的选择仅由count组成，那么这是合法的。）

SELECT COUNT(r.poll_option_id)
FROM poll_options AS p
LEFT JOIN poll_responses AS r ON (r.poll_option_id = p.id)
WHERE p.poll_id =1

或者

SELECT p. * , COUNT( r.poll_option_id ) AS voteCount,
    (SELECT COUNT(r.poll_option_id)
    FROM poll_options AS p
    LEFT JOIN poll_responses AS r ON (r.poll_option_id = p.id)
    WHERE p.poll_id =1) totalVoteCount
FROM poll_options AS p
LEFT JOIN poll_responses AS r ON ( r.poll_option_id = p.id ) 
WHERE p.poll_id =1
GROUP BY p.id
LIMIT 0 , 30

mysql连接两个表，count和sum别名

3 个答案: