时间字段按年月分组 sql语句怎么写？

[wflyxiaonian]

数据库是mysql

比如字段两列
A B
2011-10-10 100
2011-10-20 100
2012-05-15 50


查询结果为

A B
2011-10 200
2012-05 50

[Rocky_Tian2012]

to_char(A,'yyyymm') as A

sum(B)
group by A

[cosio]

select to_char(A,'yyyymm') as A,sum(B)over(partition by to_char(A,'yyyymm'))
from table

[Rotel-刘志东]

select sum(B),to_char(A,'yyyy-mm') as 'A;
from tb
group by a

[Rotel-刘志东]

---上边写错了
select sum(B),to_char(A,'yyyy-mm') as 'A'
from tb
group by a

[luoyoumou]

-- 除了使用to_char()函数外，也可以使用trunc()函数将日期部分截断到月(取每月的第一天)
select trunc(a,'mm') as a, sum(b)
from tb
group by trunc(a,'mm');

-- trunc()函数应该比to_char()函数效率更高!(有待证明)

[胖胖_多多]

with dm_gw as(
select to_date('2011-10-10', 'YYYY-MM-DD') A, '100' B from dual union all
select to_date('2011-10-20', 'YYYY-MM-DD') A, '100' B from dual union all
select to_date('2012-05-15', 'YYYY-MM-DD') A, '50'  B from dual 
)  

select distinct to_char(A,'yyyy-mm') as A,sum(B)over(partition by to_char(A,'yyyymm'))
from dm_gw order by A

--结果
2011-10 200
2012-05 50

[scrack]

select distinct to_char(A,'yyyy-mm') as A,sum(B)over(partition by to_char(A,'yyyymm'))
from dm_gw order by A

[帅蛋x]

mysql有to_char吗？