mysql中主表（联合）及其左表的计数，总和

Question

SELECT pa.prid,pa.prodid,pa.prva, ps.psna,ps.psnamid,ps.psval 
    FROM ( SELECT pid,prodid,count(prodid) as prid , 
          sum(prval) as prva
          FROM prodarpa 
          WHERE fcl = 1  GROUP BY prodid
    UNION SELECT pid,prodid,count(prodid) as prid , 
          sum(prval) as prva
          FROM prodarpb 
          WHERE fcl = 1  GROUP BY prodid ) AS pa 
    LEFT JOIN (SELECT psid,psnamid,count(psnamid) as psna,SUM(psvalue) as psval 
               FROM prosection GROUP BY psnamid ) AS ps
               ON ( pa.pid = ps.psid ) 

因此我想要如下结果：

pa.prid | pa.prodid | pa.prva | ps.psna | ps.psnamid | ps.psval 
 193        3           300      193         2          499
 200        5           100       0          0           0
  0         0            0       201         8          300
 163        10          678      163         5          453

我的意思是如果 pa.prid 值不在 ps.psna 中，那么它应该在 ps 表的每一列中显示 0 值，并且在另一种方式上相同

但它没有发生

Answer 1

如果没有数据可以从中得出结论，那就是猜测。

SELECT
      pa.prid
    , pa.prodid
    , pa.prva
    , ps.psna
    , ps.psnamid
    , ps.psval
FROM (
      SELECT
            pid
          , prodid
          , COUNT(prodid) AS prid
          , SUM(prval) AS prva
      FROM (
            SELECT
                  pid
                , prodid
                , prval
            FROM prodarpa
            WHERE fcl = 1
            UNION ALL
                  SELECT
                        pid
                      , prodid
                      , prval
                  FROM prodarpb
                  WHERE fcl = 1
            ) AS s
      GROUP BY
            pid
          , prodid
      ) AS pa
      LEFT JOIN (
            SELECT
                  psid
                , psnamid
                , COUNT(psnamid) AS psna
                , SUM(psvalue) AS psval
            FROM prosection
            GROUP BY
                  psid
                , psnamid
      ) AS ps ON (pa.pid = ps.psid)

使用 group by 时请注意，您始终指定所有非聚合列。 MySQL 确实提供了不需要的语法 - 但是使用该语法的结果不可靠，并且仅在启用 ONLY_FULL_GROUP_BY 时才允许使用该语法。

见：https://dev.mysql.com/doc/refman/5.0/en/group-by-handling.html