use northwind
go
CREATE FUNCTION GetStar(@ datetime)
RETURNS varchar(100)
AS
BEGIN
--僅一句 SQL 搞定
RETURN
(
--declare @ datetime
--set @ = getdate()
select max(star)
from
(
-- 星座,該星座開始日期所屬月,該星座開始日期所屬日
select '魔羯座' as star,1 as [month],1 as [day]
union all select '水瓶座',1,20
union all select '雙魚座',2,19
union all select '牧羊座',3,21
union all select '金牛座',4,20
union all select '雙子座',5,21
union all select '巨蟹座',6,22
union all select '獅子座',7,23
union all select '處女座',8,23
union all select '天秤座',9,23
union all select '天蠍座',10,24
union all select '射手座',11,22
union all select '魔羯座',12,22
) stars
where dateadd(day,[day]-1,dateadd(month,[month]-1,dateadd(year,datediff(year,0,@),0)))
=
(
select max(dateadd(day,[day]-1,dateadd(month,[month]-1,dateadd(year,datediff(year,0,@),0))))
from
(
select '魔羯座' as star,1 as [month],1 as [day]
union all select '水瓶座',1,20
union all select '雙魚座',2,19
union all select '牧羊座',3,21
union all select '金牛座',4,20
union all select '雙子座',5,21
union all select '巨蟹座',6,22
union all select '獅子座',7,23
union all select '處女座',8,23
union all select '天秤座',9,23
union all select '天蠍座',10,24
union all select '射手座',11,22
union all select '魔羯座',12,22
) stars
where @ >= dateadd(day,[day]-1,dateadd(month,[month]-1,dateadd(year,datediff(year,0,@),0)))
)
)
end
go
--測試
use northwind
select dbo.getstar(birthdate),count(*)
from employees
group by dbo.getstar(birthdate)
