在論壇看到 牛人們的 思路 特此收藏啊 以備學習
----------本機測試 1秒---------
用decimal(38,0),0秒:
set nocount on
goif object_id('based') is not null drop table based
if object_id('tb') is not null drop table tb
gocreate table based(id int primary key,val bigint)
insert into based select 0,1 union all
select id,power(convert(decimal(38,0),2),id) from(
select number as id from master..spt_values where type='p' and number>0 and number<57
)tinsert into based select number+57,power(convert(decimal(38,0),2),56)*power(2,number+1) from master..spt_values where type='p' and number<4
--以上求出2^1~2^60,因power函式在2^56以上時有捨去位,故分兩步處理,以乘法代之
declare @i int ,@count int,@result varchar(max),@p60 decimal(38,0),@pleft decimal(38,0)
select @i=1,@result='',@count=10000 --@count=10000就是計算2的10000次方
select @p60=val from based where id=60
select @pleft=val from based where id=@count % 60
create table tb(id int primary key,val decimal(38,0))
insert into tb select 1,1
insert into tb
select number,0 from(
select number from master..spt_values where type='p' and number>1 and number<=@count/60+2
)t--設總行數為 @count/60+2
while @i<=@count/60
begin
update t1 set t1.val= (t1.val*@p60+floor((isnull(t2.val,0)*@p60+floor(isnull(t3.val,0)*@p60/10000000000000000000))/10000000000000000000))%10000000000000000000
from tb t1 left join tb t2 on t1.id=t2.id+1 left join tb t3 on t2.id=t3.id+1
set @i=@i+1
end-- @count/60 次 @p60 相乘
update t1 set t1.val= (t1.val*@pleft+floor((isnull(t2.val,0)*@pleft+floor(isnull(t3.val,0)*@pleft/10000000000000000000))/10000000000000000000))%10000000000000000000
from tb t1 left join tb t2 on t1.id=t2.id+1 left join tb t3 on t2.id=t3.id+1
--乘以剩下的 2^(@count % 60)
select @result=@result+right('000000000000'+convert(varchar(19),val),19) from tb
where val>0
order by id desc
--select @result=convert(varchar(10),val)+@result from tb
--where and id=@count/30+2
select right(@result,len(@result)-patindex('%[1-9]%',@result)+1)
set nocount off
每次運算都*2^30，最後一次補足10000，迴圈數量變為原來的1/30了，而且每次的運算都是由系統進行，比進製運算要快很多，肯定是順間出來的。
---------------本機22秒
a的b次方
create function [dbo].[powerx](@loopnumber bigint,@loopcount int)
returns varchar(max)
asbegin
declare @str varchar(max)
declare @loop int
declare @len int
declare @num bigint
declare @add int
declare @output varchar(max)
set @str=cast(@loopnumber as varchar(max))
set @loop=1
while (@loop<@loopcount)
begin
set @output=''
set @add=0
set @len=len(@str)
while (@len!=0)
begin
set @num = cast(substring(@str,@len,1) as int)
set @num=@num*@loopnumber+@add
set @add=@num/10
set @output=cast(@num%10 as varchar(max)) +@output
set @len=@len-1
endif(@add>=1)
begin
set @output = cast(@add as varchar(max))+@output
endset @loop=@loop+1
set @str=@output
endreturn @str
enddeclare @val bigint
select @val=cast(dbo.powerx(2,25)as bigint)
select dbo.powerx(@val,400)
詳情 見論壇 ：
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在論壇看到 牛人們的 思路 特此收藏啊 以備學習 本機測試 1秒 用decimal 38,0 0秒 set nocount on goif object id based is not null drop table based if object id tb is not null drop ta...
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在論壇看到 牛人們的 思路 特此收藏啊 以備學習 本機測試 1秒 用decimal 38,0 0秒 set nocount on goif object id based is not null drop table based if object id tb is not null drop ta...
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