ALTER FUNCTION [dbo].[DataToString]
(
  @Data  datetime
)
RETURNS varchar(20)
AS
BEGIN
  
  DECLARE @Appo varchar(20)

  SET @Appo = convert(varchar(20) ,@data, 120)

  SET @Appo = Substring(@Appo,1,4) + Substring(@Appo,6,2) + Substring(@Appo,9,2) + Substring(@Appo,12,2) + Substring(@Appo,15,2) + Substring(@Appo,18,2) 

  -- Return the result of the function
  RETURN @Appo

END