MS SQL2005+ : calcule le digit de contrôle pour un EAN13 / Compute the checksum digit for an EAN13

checksum_ean13.sql

create function [E].[compute_ean13fromgencod](@gencod as varchar(12))
returns varchar(13)
as 
begin
declare @calcul bigint, @temp int
declare @ret varchar(13)
 
if(len(@gencod)<>12)
  return @gencod
 
set @calcul = 0
set @calcul = @calcul + convert(int, substring(@gencod, 12, 1))
set @calcul = @calcul + convert(int, substring(@gencod, 10, 1))
set @calcul = @calcul + convert(int, substring(@gencod, 8, 1))
set @calcul = @calcul + convert(int, substring(@gencod, 6, 1))
set @calcul = @calcul + convert(int, substring(@gencod, 4, 1))
set @calcul = @calcul + convert(int, substring(@gencod, 2, 1))
set @calcul=@calcul*3
 
set @temp = 0
set @temp = @temp + convert(int, substring(@gencod, 11, 1))
set @temp = @temp + convert(int, substring(@gencod, 9, 1))
set @temp = @temp + convert(int, substring(@gencod, 7, 1))
set @temp = @temp + convert(int, substring(@gencod, 5, 1))
set @temp = @temp + convert(int, substring(@gencod, 3, 1))
set @temp = @temp + convert(int, substring(@gencod, 1, 1))
 
set @calcul=@calcul+@temp
 
if(@calcul % 10) = 0
  set @ret = @gencod + '0'
else
	set @ret = @gencod + convert(varchar(1), 10 - (@calcul % 10))
 
return @ret
 
end