Hàm tạo số 0 theo định dạng

GO
/****** Object:  UserDefinedFunction [dbo].[Format_Number_Zero]  
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- select [dbo].[Format_Number_Zero](4,'0000')  
-- ket qua la 0004
CREATE FUNCTION [dbo].[Format_Number_Zero]
(
    -- Add the parameters for the function here
    @so int
,    @format nvarchar(20)
)
RETURNS nvarchar(20)
AS
BEGIN
    DECLARE @KQ nvarchar(20)
    -- Declare the return variable here
       
    SELECT @KQ=RIGHT(@format + CAST(@so as varchar), LEN(@format))

    RETURN @KQ
    
END