Question

我想计算两个表中相同用户ID的出现次数。 jos_findme表中包含所有用户。另外两个也有“用户ID”列。

但我想要两张桌子的整体数量。我试过这个，但它不起作用？

SELECT 
    c.user_id, count(c.user_id) AS counter
FROM
    jos_findme as c
        LEFT JOIN
    jos_findme_bestof as b ON b.user_id = c.user_id
        LEFT JOIN
    jos_findme_pair as p ON p.user_id = c.user_id
WHERE
    c.user_id > 0
GROUP BY c.user_id
ORDER BY counter DESC
LIMIT 10

所有表都有“user_id”列。我只想在表“jos_findme_bestof”和“jos_findme_pair”中计算它们

Answer 1

相关的子查询在这里很有用：

SELECT c.user_id, 
       (SELECT Count(*) 
        FROM   jos_findme_bestof b 
        WHERE  b.user_id = c.user_id), 
       (SELECT Count(*) 
        FROM   jos_findme_pair p 
        WHERE  p.user_id = c.user_id) 
FROM   jos_findme c

Answer 2

我认为你可以这样做：

SELECT AA.user_id, AA.Acounter + BB.Bcounter
from     (SELECT a.user_id, count(a.user_id) AS Acounter
          FROM jos_findme_bestof as a
          GROUP BY a.user_id) as AA 
     Join  
        (SELECT b.user_id, count(b.user_id) AS Bcounter
          FROM jos_findme_pair as b
          GROUP BY b.user_id) as BB
     on AA.user_id = BB.user_id

如果你想要所有的id（意思是jos_findme_pair中的id不在jos_findme_bestof中） - 使用FULL OUTER JOIN

Answer 3

试试这个

SELECT c.user_id,
       Users1 = (SELECT COUNT(*) FROM jos_findme_bestof b WHERE b.user_id = c.user_id),
       Users2 = (SELECT COUNT(*) FROM jos_findme_pair p WHERE p.user_id = c.user_id),
       TotalUser = (SELECT COUNT(*) FROM jos_findme_bestof b WHERE b.user_id = c.user_id)
       +
       (SELECT COUNT(*) FROM jos_findme_pair p WHERE p.user_id= c.user_id)
FROM   
jos_findme c

下面， Users1将返回jos_findme_bestof的所有用户 Users2将返回jos_findme_pair的所有用户 TotalUser将计算两个表

希望它会对你有所帮助！感谢。

Answer 4

试试这个：

SELECT c.user_id, (IFNULL(b.bCount, 0) + IFNULL(p.pCount, 0)) AS counter
FROM jos_findme AS c
LEFT JOIN (SELECT b.user_id, COUNT(1) bCount 
           FROM jos_findme_bestof b 
           GROUP BY b.user_id 
         ) AS b ON b.user_id = c.user_id 
LEFT JOIN (SELECT p.user_id, COUNT(1) pCount 
           FROM jos_findme_pair p 
           GROUP BY p.user_id 
         ) AS p ON p.user_id = c.user_id 
WHERE c.user_id > 0
GROUP BY c.user_id
ORDER BY counter DESC
LIMIT 10

选择两个表的用户数

4 个答案: