如何写这个函数作统计？有点类似group by

Question

--统计函数
create function getcitynum(
@province varchar(10)
)returns int
as
begin
  return((select count(*) from tb where province=@province))
end
go--查询
select province,dbo.getcitynum(province) citynum,city  from tb

Answer 1

--或者直接统计:select province,(select count(*) from tb where province=a.province) citynum,city  from tb a

Answer 2

create function getcitynum(
@province as varchar(10)
)
returns
int
as
return select count(*) from tb where tb.province = @province

Answer 3

select province,count(*) from tb where group by province