實現楊輝三角

CREATE proc #pr_YangHui
@c int
as
 /* SQL實現顯示楊輝三角 */
 /* 版本: 1.0 */
 /* 作者: Haiwer */
 /* 版權所有 */
 /* 2006.05.10 */
set nocount on
if @c<2 return --兩層以下就不排了
declare @i int
declare @j int
declare @sql varchar(8000)
declare @sql1 varchar(8000)
declare @sql2 varchar(8000)
create table #(id int IDENTITY(1,1),a50000 bigint)
insert #(a50000) values (1) --第一層
set @i=2
while @i<=@c
begin
 --為了實現動態層，只好動態修改臨時表結構
 set @sql='alter table # add a'+cast(50000+@i-1 as varchar(10))+' bigint,a'+cast(50000-@i+1 as varchar(10))+' bigint' 
 exec (@sql)
 set @sql1=''
 set @sql2=''
 set @j=@i-1
 while @j>=0
 begin
 --這里判斷有點亂
 if @j=0
 set @sql1=@sql1+',a'+cast(50000-@j as varchar(10))
 else
 set @sql1=@sql1+',a'+cast(50000-@j as varchar(10))+',a'+cast(50000+@j as varchar(10))
 if @j=@i-1
 set @sql2=@sql2+',1,1'
 else
 if @j=0
 set @sql2=@sql2+',a'+cast(50000-@j-1 as varchar(10))+'+a'+cast(50000-@j+1 as varchar(10))
 else
 set @sql2=@sql2+',a'+cast(50000-@j-1 as varchar(10))+'+a'+cast(50000-@j+1 as varchar(10))+',a'+cast(50000+@j-1 as varchar(10))+'+a'+cast(50000+@j+1 as varchar(10))
 
 set @j=@j-2
 end
 --去掉多余的逗號
 set @sql1=right(@sql1,len(@sql1)-1)
 set @sql2=right(@sql2,len(@sql2)-1)
 set @sql=cast(@i-1 as varchar(10))
 exec('insert #('+@sql1+') select '+@sql2+' from # where id='+@sql)
 set @i=@i+1
end

set @i=50000-@c+1
set @j=50000+@c-1
set @sql=''
--去最長的數據，就是為了節省顯示空間
select @sql1=CAST(len(cast(max(a50000) as varchar(50)))+1 AS VARCHAR(10)) from #
while @i<=@j
begin
 set @sql=@sql+',isnull(cast(a'+cast(@i as varchar(10))+' as varchar('+@sql1+')),'''')'
 set @i=@i+1
end
exec ('select id'+@sql+' from # order by id')
drop table #

GO
 
--調用
exec #pr_YangHui 8