mysql查询问题

Question

mysql查询语句实现

想要得到如下查询结果：

mysql中一般是通过什么函数实现该功能?

我是这样实现的感觉逻辑有些混乱:

结果:

有没有更好的写法呢?

Answer 1

SELECT 
    year, 
    sum( if( month = 1, amount, 0 ) ) AS m1,  
    sum( if( month = 2, amount, 0 ) ) AS m2,  
    sum( if( month = 3, amount, 0 ) ) AS m3,  
    sum( if( month = 4, amount, 0 ) ) AS m4
FROM 
    statistics
GROUP BY 
    year;