[MSSQL]文字列指定長文字の削除

-- 
--@count <=0  
create function fun_Remove(@txt nvarchar(2000),@index int,@count int)
returns nvarchar(2000)
as
begin
    declare @len int
    set @len=len(@txt)
    --@count <=0  
    if @count<1 begin
        if @index <1 begin
            return ''
        end
        return substring(@txt,0,@index)
    end
    if @index+@count<1 begin
        -- <1
        return @txt
    end else if @index+@count>=@len begin
        -- 
        if @index<1 begin
            return ''
        end
        return substring(@txt,0,@index)
    end
    --  
    if @index<1 begin
        return substring(@txt,@index+1,@len-@index-@count)
    end

    return substring(@txt,0,@index)+substring(@txt,@index+@count,@len-@index-@count+1)
end
go

select dbo.fun_Remove('http://www.naoqiu.com',5,1) 

--  ：http//www.naoqiu.com