SQL Server 等差数列求和

1+2+3 +...+100这种问题，首相想到的是用循环解决。代码如下

;declare @v_i int = 1,@v_sum int = 0
while @v_i <=  100
    begin
        set @v_sum = @v_sum + @v_i
        set @v_i = @v_i + 1
    end
print @v_sum

最近发现可以用with as特性同样可以解决

;with a(v) as(
    select 1 
    union all
    select v+1 from a where v+1<=100)
select sum(v) from a