在SQL SERVER 2005中實(shí)現(xiàn)素?cái)?shù)計(jì)算

2024-08-31 00:50:11

字體：大中小

供稿：網(wǎng)友

　　我將提出一個挑戰(zhàn)，誰能用sqlseerver提出計(jì)算素?cái)?shù)最好的方法，我用了一個新的特點(diǎn)cte和某些tsql實(shí)現(xiàn)，但均不理想，前者（cte）有限制，而后者（tsql）產(chǎn)生一百萬個素?cái)?shù)用了7分種你可以干的更好么？這兒是我的一些代碼段落

　　（tsql實(shí)現(xiàn)）

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 < 1000000
begin
if not exists (select 1 from @prime where @number % prime = 0 and prime < sqrt(@number) )
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 %11 = 10 then 2
else 1 end
end
select @pc

　　和

　　（cte實(shí)現(xiàn)）

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 %11 = 10 then 2
else 1 end
from seq s
where number < 32767
)
, prime as (
select s.number
from seq s
where not exists ( select 1 from seq s2 where s2.number < s.number and (s.number) % s2.number = 0)
)
select *
from prime
option (maxrecursion 32767)