GROUP BY用柱SQL的值

Question

我想通过类型来显示用于给定用户的百分比（M或C） 我试图与此查询：

SELECT TYPE,user_name,pourcentage_c,pourcentage_m,id_user, 
     COUNT(TYPE) AS crtitique ,COUNT(TYPE) AS majeur 
FROM stat_alert 
LEFT OUTER JOIN user_qdf ON user_qdf.`id` = id_user 
WHERE user_qdf.`id`=id_user AND TYPE='C' 
GROUP BY id_user 
UNION ALL 
SELECT TYPE,user_name,pourcentage_c,pourcentage_m,id_user, 
     COUNT(TYPE) AS crtitique,COUNT(TYPE) AS majeur 
FROM stat_alert 
LEFT OUTER JOIN user_qdf ON user_qdf.`id` = id_user 
WHERE user_qdf.`id`=id_user AND TYPE='M' 
GROUP BY id_user 

我想在同一行显示百分比和关键的数量和单个用户

Answer 1

这应该是重要的（现在不能测试）

SELECT TYPE,user_name,pourcentage_c,pourcentage_m,id_user, 
    SUM(CASE user_qdf_c.TYPE WHEN 'C' 1 ELSE 0 END) AS crtitique, 
    SUM(CASE user_qdf_m.TYPE WHEN 'M' 1 ELSE 0 END) AS majeur 
FROM stat_alert 
LEFT OUTER JOIN user_qdf user_qdf_c ON user_qdf_c.`id` = id_user AND TYPE='C' 
LEFT OUTER JOIN user_qdf user_qdf_m ON user_qdf_m.`id` = id_user AND TYPE='M' 
GROUP BY id_user 

这个想法不是使用COUNT，而是使用SUM。

编辑这可以被改写更好，与只使用一个LEFT JOIN（这意味着很多更好的表现！）看到@ SashiKant的，和@ bluefeet的解决方案。

Answer 2

尝试此::

SELECT 
TYPE, 
user_name,pourcentage_c,pourcentage_m,id_user,COUNT(TYPE) AS crtitique ,COUNT(TYPE) AS majeur 

FROM stat_alert LEFT OUTER JOIN user_qdf ON user_qdf.id = id_user和user_qdf.id = id_user TYPE = 'C' 或TYPE = 'M' GROUP BY id_user

Answer 3

你应该能够使用类似的东西（这基本上是一个PIVOT功能）。这会在您的user_qdf表上执行一次JOIN一次。然后，您可以用CASE语句来获取计数（使用SUM），为每个不同的TYPE值的应用聚合函数：

SELECT TYPE, 
    user_name, 
    pourcentage_c, 
    pourcentage_m, 
    id_user, 
    sum(case when TYPE ='C' then 1 else 0 end) AS crtitique, 
    sum(case when TYPE ='M' then 1 else 0 end) AS majeur 
FROM stat_alert 
LEFT OUTER JOIN user_qdf 
    ON user_qdf.`id` = id_user 
WHERE user_qdf.`id`=id_user 
    AND type IN ('M', 'C') 
GROUP BY id_user 

Answer 4

试试这个：

SELECT user_name, pourcentage_c, pourcentage_m, id_user, 
     COUNT(1) AS crtitique, COUNT(1) AS majeur 
FROM stat_alert 
LEFT OUTER JOIN user_qdf ON user_qdf.id = id_user 
GROUP BY id_user, TYPE