SUM和GROUP来自两个表

Question

我有两张桌子 - 一张用于每日收入，一张用于每日费用。

每个日期都有一个收入

+------------+---------+
| date       | revenue |
+------------+---------+
| 2017-01-04 | 100     |
| 2017-01-05 | 150     |
| 2017-01-06 | 200     |
...

没有，每个日期有一个或多个费用。

+------------+---------+
| date       | cost    |
+------------+---------+
| 2017-01-04 | 17      |
| 2017-01-04 | 32      |
| 2017-01-06 | 55      |
| 2017-01-07 | 10      |
...

我现在想按月对数据进行分组......结果应该是一个表格，列出了每个月的总收入以及总计费用：

+---------+----------+-------+
| month   | revenue  | costs |
+---------+----------+-------+
| 2017-01 | 4400,00  | 80,00 |
| 2017-02 | 2100,00  | 70,00 |
| 2017-03 | 5500,00  | 90,00 |
...

我该怎么做？

Answer 1

我认为这是你的期望。

表格

CREATE TABLE T1
(
   date datetime,
   revenue int
);

CREATE TABLE T2
(
   date datetime,
   cost int
);


INSERT INTO T1 (date,revenue)
VALUES 
('2017-01-04',100),
('2017-01-05',150),
('2017-01-06',200),
('2017-02-06',200);



INSERT INTO T2 (date,cost)
VALUES 
('2017-01-04',17),
('2017-01-04',32),
('2017-01-06',55),
('2017-01-07',10),
('2017-02-07',10);

<强>查询

SELECT T1.MONTH,revenue,costs FROM
(
  SELECT DATE_FORMAT(date, '%Y-%m') AS 'month'
         ,SUM(revenue) AS 'revenue'
  FROM T1
  GROUP BY DATE_FORMAT(date, '%Y-%m')
) AS T1
INNER JOIN 
(
  SELECT DATE_FORMAT(date, '%Y-%m') AS 'month'
         ,SUM(cost)  AS 'costs'
  FROM T2
  GROUP BY DATE_FORMAT(date, '%Y-%m')
) AS T2
ON T1.month = T2.month

SQLFiddle

Answer 2

E.g：

SELECT DATE_FORMAT(date,'%Y-%m') yearmonth
     , COALESCE(SUM(CASE WHEN type = 'revenue' THEN amount END),0) revenue
     , COALESCE(SUM(CASE WHEN type = 'cost' THEN amount END),0) cost
  FROM 
     ( SELECT date, 'revenue' type, revenue amount FROM revenue
       UNION ALL
       SELECT date, 'cost', cost FROM costs
     ) x
 GROUP
    BY yearmonth;