Question

sql 一张表中 一条sql语句如何count多条数据

一张表a中有b1,b2,b3三个字段 如何用一条sql语句统计这三个字段的总数 count能实现吗
提问有误 不好意思 表a中
select * from a
where 1=1
and b=1
and b=2
and b=3
如何count这三个条件

Answer 1

select (select count(1) from a where b=1) as b1,(select count(1) from a where b=2) as b2,(select count(1) from a where b=3) as b3

Answer 2

select count(*) from a;
select count(b1),count(b2),count(b3) from a
直接加入就是了。
select count（*） where 你的条件 from a

Answer 3

下面这样就行了

select count(*),b from a
where 1=1
and (b=1
or b=2
or b=3)
group by b