Question

一个简单的sql语句我就是写不出啊

各位大神请问我想得到11-20有3条。【就是a字段加起来】11-21有3条。怎么写啊。

Answer 1

select sum(a)
from 表
where e='2012-11-21'

Answer 2

select e,sum(a) from table
group by e

Answer 3

select a,e,count(*) from table group by a,e

Answer 4

select sum(a) from table where right(e,5)='11-20'