在SQLSERVER2005中实现素数计算_PHP教程
- WBOY원래의
- 2016-07-13 17:00:37755검색
我将提出一个挑战，谁能用SQLSEERVER提出计算素数最好的方法，
我用了一个新的特点CTE和某些TSQL实现，但均不理想，前者（CTE）有限制，而后者（TSQL）产生一百万个素数用了7分种
你可以干的更好么？
这儿是我的一些代码段落
（TSQL实现）
set nocount on
declare @prime table (prime int not null primary key)
--insert into @prime values (2)
--insert into @prime values (3)
--insert into @prime values (5)
--insert into @prime values (7)
--insert into @prime values (11)
declare @number int, @pc int
set @number = 13
set @pc = 1
while @pc begin
if not exists (select 1 from @prime where @number % prime = 0 and prime begin
insert into @prime select @number
set @pc = @pc 1
end
set @number = @number
case when @number %2 = 1 then 2
when @number %3 = 2 then 2
when @number %5 = 4 then 2
when @number %7 = 6 then 2
when @number = 10 then 2
else 1 end
end
select @pc
和
（CTE实现）
with seq
as( select 13 number
union all
select s.number
case when s.number %2 = 1 then 2
when s.number %3 = 2 then 2
when s.number %5 = 4 then 2
when s.number %7 = 6 then 2
when s.number = 10 then 2
else 1 end
from seq s
where number )
, prime as (
select s.number
from seq s
where not exists ( select 1 from seq s2 where s2.number )
select *
from prime
option (MAXRECURSION 32767)