GROUP BY具有列SQL的值

Question

我想按类型（M或C）显示给定用户的百分比 我尝试了这个查询：

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

我想在同一行显示单个用户的关键和重要的百分比和数量

Answer 1

你应该可以使用类似的东西（这基本上是一个PIVOT函数）。这会在JOIN表上执行一次user_qdf。然后，您应用带有CASE语句的聚合函数来获取每个不同SUM值的计数（使用TYPE）：

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 2

这应该有效（现在无法测试）

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。

编辑这可以更好地重写，仅使用一个LEFT JOIN（这意味着很多更好的性能！）请参阅@ SashiKant和@ bluefeet的解决方案。< / p>

Answer 3

试试这个::

  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 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