优化查询以从一个表的两个不同列和不同行计算总数

Question

表帐户

Id    price     currency      date 
1      10        USD         2013-01-12  
2      200       GBP         2013-01-13 
3      30        GBP         2013-01-14 
4      85        USD         2013-01-20 
5      80        GBP         2013-01-25 
6     120        GBP         2013-01-30 
7     180        GBP         2013-01-31 
8     100        GBP         2013-02-04 

我想从这样的一个月算起来：

Total:  USD     95  
Total:  GBP     610

Answer 1

您只需使用GROUP BY和汇总功能 SUM()来计算其总数。

SELECT  currency, SUM(price) totalPrice
FROM    tableName
GROUP   BY currency

• SQLFiddle Demo
• SQLFiddle Demo (by month)
• SQLFiddle Demo (by month and year)