> -----Original Message----- > From: Tomasz Korycki [mailto:[EMAIL PROTECTED] > Sent: 11 August 2003 05:26 > To: [EMAIL PROTECTED] > Subject: OT: Re: MySQL field data type for ISBN numbers > > > At 21:08 2003-08-10, you wrote: > >On Sun, Aug 10, 2003 at 05:25:05PM -0700, James Johnson wrote: > > > > > > I have a MySQL database for books. The ISBN field is set > as varchar(15) and > > > I've put a test ISBN number in of 1-1111-111-11. > > > >Note that ISBN numbers are a maximum of 13 characters, not 15. Ten > >digits, three dashes. If you really want to save space, the > last digit > >is just a check digit and can always be determined through a > formula on > >the other digits, so as long as you verify every ISBN before > you INSERT > >it, you can save another digit. > > Hmmm...And how do You come up with an 'X' as the last digit, > as many books > on the shelves around me do? > I don't know which particular check digit algorithm is used for ISBNs but the mod-11 algorithm uses the digits 0-9 and X for 10.
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