Question

我有三张桌子，我希望按月从三张桌子中加总值。

数据库的结构：

1)costs_1

-id
-total
-updated_at(timestamp)

2)costs_2

-id
-total_1
-updated_at_1(timestamp)

3)costs_3
    -id
    -total_2
    -updated_at_2(timestamp)

结果表的结构：1）总计; 2）TOTAL_1; 3）TOTAL_2; 4）月

我的代码适用于两个表，但不知道如何适应它

＆＃13;

        SELECT t1.y year,
           t1.m month,
           COALESCE(t1.total, 0),
           COALESCE(t2.total, 0)
               
        FROM
        (
            SELECT YEAR(date_month) y, 
                   MONTH(date_month) m, 
                   SUM(total) total
            FROM market_costs
            GROUP BY YEAR(date_month), MONTH(date_month) 
        ) t1
        LEFT JOIN
        (
            SELECT YEAR(date_month) y, 
                   MONTH(date_month) m, 
                   SUM(total) total
            FROM general_costs
            GROUP BY YEAR(date_month), MONTH(date_month) 
        ) t2 ON t1.y = t2.y and t1.m = t2.m
        
           UNION
        
        SELECT t2.y year,
               t2.m month,
               COALESCE(t1.total, 0),
               COALESCE(t2.total, 0)
        FROM
        (
            SELECT YEAR(date_month) y, 
                   MONTH(date_month) m, 
                   SUM(total) total
            FROM market_costs
            GROUP BY YEAR(date_month), MONTH(date_month) 
        ) t1
        RIGHT JOIN
        (
            SELECT YEAR(date_month) y, 
                   MONTH(date_month) m, 
                   SUM(total) total
            FROM general_costs
            GROUP BY YEAR(date_month), MONTH(date_month) 
        ) t2 ON t1.y = t2.y and t1.m = t2.m

＆＃13;

Answer 1

使用UNION ALL合并3个表，然后对数据进行分组：

SELECT
      YEAR(t1.date_month) y
    , MONTH(t1.date_month) m
    , SUM(t1.total) total
    , SUM(t1.total_1) total_1
    , SUM(t1.total_2) total_2
FROM (
      SELECT
            date_month
          , total
          , NULL as total_1
          , NULL as total_2
      FROM costs
      UNION ALL
      SELECT
            date_month
          , NULL as total
          , total_1
          , NULL as total_2
      FROM costs_1
      UNION ALL
      SELECT
            date_month
          , NULL as total
          , NULL as total_1
          , total_2
      FROM costs_2
      ) t1
GROUP BY
      YEAR(t1.date_month)
    , MONTH(t1.date_month)

<强>加入

SELECT
      YEAR(t1.date_month) y
    , MONTH(t1.date_month) m
    , SUM(t1.total) total
    , SUM(t1.total_1) total_1
    , SUM(t1.total_2) total_2
FROM (
      SELECT
            date_month
          , total
          , NULL as total_1
          , NULL as total_2
      FROM costs
      UNION ALL
      SELECT
            date_month
          , NULL as total
          , total as total_1 -- changed
          , NULL as total_2
      FROM costs_1
      UNION ALL
      SELECT
            date_month
          , NULL as total
          , NULL as total_1
          , total as total_2  -- changed
      FROM costs_2
      ) t1
GROUP BY
      YEAR(t1.date_month)
    , MONTH(t1.date_month)

使用连接三个表

1 个答案: