在日期字段中按月分组（字符串）

Question

一个带有字符串字段的表，其中存储了日期（不建议我更改字段类型。这会导致危险）。

+--+----------+------+
|id|date      |amount|
+--+----------+------+
|1 |23-03-2014|5000  |
+--+----------+------+
|2 |25-03-2014|3000  |
+--+----------+------+
|3 |21-04-2014|3000  |
+--+----------+------+
|4 |25-04-2014|4000  |
+--+----------+------+

我想编写一个模型函数，它将返回表中按月分组的金额总和。我该怎么办？它将显示输出

03 - 8000
04 - 7000

Answer 1

SELECT MONTH(date_field) as mon, SUM(amount) as total FROM table_name GROUP BY MONTH(date_field);

更新

SELECT SUBSTR(date_field,6,2) as mon, SUM(amount) as total FROM table_name GROUP BY mon;

Answer 2

您可以尝试以下查询

SELECT SUM(amount) FROM table GROUP BY MONTH(date)

Answer 3

尝试MONTH()

SELECT MONTH(date),SUM(amount) FROM table GROUP BY MONTH(date)