跪求一条sql统计语句

[haitao00244]

假设有一张A表

table A
id name flag
---------------------------
1 'a' true
2 'b' false
3 'c' true
4 'd' true


现在想用一条sql语句实现统计 flag=false的数量和 flag=true的数量

期望结构如下：select count(id) as y,count(id) as n from A .....

[zcs_1]

select flag, count(*) from a group by flag

[zcs_1]

select flag, count(*) from a group by flag

[超叔csdn]

select count(case when flag='false' then id end ) as y,count(case when flag='true' then id end ) as n from A

[超叔csdn]

select count(case when flag='false' then id end ) as y,count(case when flag='true' then id end ) as n from A

[waterfirer]

select sum(decode(flag,'true',1,0)) as y, sum(decode(flag,'flase',1,0)) as n from A

[inthirties]

select sum(decode(flag, 'true', 1, 0)) as y, sum(decode(flag, 'false', 1, 0)) n from A;