初学者——数据库有关问题
日期：2014-05-20 浏览次数：20753 次
菜鸟求助——数据库问题
怎么实现这样的查询效果
year M1 M2 M3 M4
1991 1.1 1.2 1.3 1.4
1992 1.1 1.2 1.3 1.4
除了这中方法select year , min(mount) M1, min(mount)+0.1 M2............
求赐教：
------解决方案--------------------
怎么实现这样的查询效果
year M1 M2 M3 M4
1991 1.1 1.2 1.3 1.4
1992 1.1 1.2 1.3 1.4
除了这中方法select year , min(mount) M1, min(mount)+0.1 M2............
求赐教：
------解决方案--------------------
select
year,
sum(if(M=1, mount,0)) AS M1,
sum(if(M=2, mount,0)) AS M2,
sum(if(M=3, mount,0)) AS M3,
sum(if(M=4, mount,0)) AS M4,
sum(if(M=5, mount,0)) AS M5,
sum(if(M=6, mount,0)) AS M6,
sum(if(M=7, mount,0)) AS M7,
sum(if(M=8, mount,0)) AS M8,
sum(if(M=9, mount,0)) AS M9,
sum(if(M=10, mount,0)) AS M10,
sum(if(M=11, mount,0)) AS M11,
sum(if(M=12, mount,0)) AS M12
from tb
group by year
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