按月加入 3 个表 SUM 组答案

【问题标题】：JOIN 3 tables SUM group by month按月加入 3 个表 SUM 组
【发布时间】：2018-09-11 04:41:28
【问题描述】：

我正在尝试按月加入 3 个表组并计算 2 个表的总和。我可以加入所有表格，但总和不正确。我的桌子：

表月份

表格发票

餐桌购买

我的查询：

$query = $this->db->query("SELECT month.month_name as month, 
    SUM(table_purchase.subtotal) AS total_pur,
    SUM(table_invoice.subtotal) AS total_inv  
    FROM month 
    LEFT JOIN table_purchase ON (month.month_num = MONTH(table_purchase.date_pur) AND YEAR(table_purchase.date)= '2018')
    LEFT JOIN table_invoice ON (month.month_num = MONTH(table_invoice.date_inv) AND YEAR(table_invoice.date)= '2018')
    GROUP BY month.month_name ORDER BY month.month_num");

结果应该是这样的：

+---------------------------+
|Month| Total Inv| Total Pur|
+---------------------------+
| Jan |    30    |  80      |
+---------------------------+
| Feb |    90    |  48      |
+---------------------------+
| Mar |   110    |  42      |
+---------------------------+
| Apr |    60    |  96      |
+---------------------------+
| May |  null    |  72      |
+---------------------------+
| Jun |    30    |  56      | 
+---------------------------+
| Jul |    32    |  10      |
+---------------------------+
| Agt |    48    |  36      |
+---------------------------+
| Sep |  null    | null     |
+---------------------------+
| Okt |  null    | null     |
+---------------------------+
| Nov |  null    | null     |
+---------------------------+
| Des |  null    | null     |
+---------------------------+

但是几个月来我得到了错误的金额。我认为它会重演。我已经尝试过类似的内部连接，然后加入。但我仍然得到了错误的金额。如何使它正确？谢谢

编辑，我表中的数据：

月份：

INSERT INTO `month` (`month_num`, `month_name`) VALUES
(1, 'Jan'),
(2, 'Feb'),
(3, 'Mar'),
(4, 'Apr'),
(5, 'May'),
(6, 'Jun'),
(7, 'Jul'),
(8, 'Agt'),
(9, 'Sep'),
(10, 'Okt'),
(11, 'Nov'),
(12, 'Des');

table_invoice

INSERT INTO `table_invoice` (`id`, `ref`, `med`, `unit_price`, `qty`, `subtotal`, `customer`, `date`, `grandtotal`) VALUES
(80, 'JMBSErmmo0', 'Adona', 15000, 1, 15000, 'Melinda', '2018-08-09', 29000),
(81, 'JMBSErmmo0', 'Asam Mefenamat', 4000, 1, 4000, 'Melinda', '2018-08-09', 29000),
(82, 'JMBSErmmo0', 'Salbutamol', 10000, 1, 10000, 'Melinda', '2018-08-09', 29000),
(87, 'xl23Q6whsP', 'Salbutamol', 10000, 3, 30000, 'Melinda', '2018-01-10', 30000),
(90, '9ab7RcZHma', 'Adrome', 15000, 6, 90000, 'Doni', '2018-02-14', 90000),
(91, 'fAMEjr9rA0', 'Ambroxol', 22000, 5, 110000, 'Amirullah', '2018-03-14', 110000),
(92, 'so5518T1vI', 'Salbutamol', 10000, 6, 60000, 'Doni', '2018-04-18', 60000),
(95, 'M5mhiUJs5y', 'Adona', 15000, 1, 15000, 'Melinda', '2018-08-22', 19000),
(96, 'M5mhiUJs5y', 'Asam Mefenamat', 4000, 1, 4000, 'Melinda', '2018-08-22', 19000),
(97, 'VS27jjD5Ze', 'Ambroxol', 22000, 1, 22000, 'Pitaloka', '2018-07-18', 32000),
(98, 'VS27jjD5Ze', 'Stimuno', 10000, 1, 10000, 'Pitaloka', '2018-07-18', 32000),
(99, 'nyptFm9i43', 'Stimuno', 10000, 3, 30000, 'Andi', '2018-06-13', 30000),
(100, '3ilz1ZvPj5', 'Stimuno', 10000, 11, 110000, 'Andi', '2017-05-17', 110000);

table_purchase

INSERT INTO `table_purchase` (`id`, `ref`, `med`, `unit_price`, `qty`, `subtotal`, `supplier`, `date`, `grandtotal`) VALUES
(3, 'L8BvtCyFDZ', 'Salbutamol', 6000, 3, 18000, 'Bina Jaya Apotek', '2018-08-11', 24000),
(4, 'L8BvtCyFDZ', 'Stimuno', 6000, 1, 6000, 'Bina Jaya Apotek', '2018-08-11', 24000),
(8, 'pwoaFcmGVs', 'Asam Mefenamat', 4000, 12, 48000, 'Bina Jaya Apotek', '2018-02-22', 48000),
(9, '96kHYMepS9', 'Salbutamol', 6000, 7, 42000, 'Bina Jaya Apotek', '2018-03-21', 42000),
(10, 'Tbb6pLVCJr', 'Ambroxol', 20000, 4, 80000, 'Bina Jaya Apotek', '2018-01-24', 80000),
(11, 'fdMGrBa4nS', 'Stimuno', 6000, 16, 96000, 'Bina Jaya Apotek', '2018-04-18', 96000),
(12, 'aDxtUA0rsc', 'Adrome', 12000, 6, 72000, 'Bina Jaya Apotek', '2018-05-09', 72000),
(13, '5UCwWCC7Yb', 'Asam Mefenamat', 4000, 3, 12000, 'Bina Jaya Apotek', '2018-08-16', 12000),
(14, 'KCZxZ1MqID', 'Ambroxol', 20000, 2, 40000, 'Bina Jaya Apotek', '2018-07-18', 40000),
(15, 'Ar9235n1ny', 'Adrome', 12000, 3, 36000, 'Kenanga Apotek', '2018-06-06', 56000),
(16, 'Ar9235n1ny', 'Ambroxol', 20000, 1, 20000, 'Kenanga Apotek', '2018-06-06', 56000);

【问题讨论】：

显示你的3个表的数据，否则很难猜到，因为你的查询没问题
我已经编辑了这个问题。请查收，谢谢

标签： mysql join left-join

【解决方案1】：

在不同的子条款中计算发票和购买的总和，然后与您的月表进行左连接

SELECT m.month_name as month, 
   i.total_inv, 
   p.total_pur
FROM month m
LEFT JOIN (SELECT MONTH(date_inv) as month, 
            SUM(subtotal) as total_inv  
            FROM table_invoice
            WHERE YEAR(date_inv)= '2018'
            GROUP BY month) i  ON (m.month_num = i.month)    
LEFT JOIN (SELECT MONTH(date_pur) as month, 
            SUM(subtotal) as total_pur
            FROM  table_purchase 
            WHERE YEAR(date_pur)= '2018'
            GROUP BY month) p ON (m.month_num = p.month )
ORDER BY m.month_num

【讨论】：

【解决方案2】：

您的问题正在发生，因为 JOIN 正在产生乘法效应；例如，当同一个月有 3 张发票和 2 次购买时，您会得到 6 行数据（3*2），导致所有值都太大。您需要分别汇总每年每个月的所有采购和发票，然后将结果 JOIN 到月份表中：

SELECT m.month_name as month, 
    p.total_pur,
    i.total_inv  
    FROM month m
    LEFT JOIN (SELECT YEAR(date) AS y, MONTH(date) AS m, SUM(subtotal) AS total_pur FROM table_purchase GROUP BY y, m) p
        ON m.month_num = p.m AND p.y = 2018
    LEFT JOIN (SELECT YEAR(date) AS y, MONTH(date) AS m, SUM(subtotal) AS total_inv FROM table_invoice GROUP BY y, m) i
        ON m.month_num = i.m AND i.y = 2018
    GROUP BY m.month_name ORDER BY month

【讨论】：