2.使用T-SQL语言，输出：

*

***

*****

*******

*********

declare @i as int
set @i = 1
while @i <= 20
begin
    declare @j as int
    set @j = 1
    declare @str as varchar(20)
    set @str = ''
    while @j <= @i
    begin
        set @str = @str +  '*'
        set @j = @j + 1
    end
    print @str
    set @i = @i + 2
end