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isbn.c | ||
isbn.sql | ||
issn.c | ||
issn.sql | ||
Makefile | ||
README |
This directory contains definitions for a couple of PostgreSQL external types, for a couple of international-standard namespaces: ISBN (books) and ISSN (serials). Rather than just using a char() member of the appropriate length, I wanted my database to include the validity-checking that both these numbering systems were designed to encompass. A little bit of research revealed the formulae for computing the check digits, and I also included some validity constraints on the number of hyphens. The internal representation of these types is intended to be compatible with `char16', in the (perhaps vain) hope that this will make it possible to create indices of these types using char16_ops. These are based on Tom Ivar Helbekkmo's IP address type definition, from which I have copied the entire form of the implementation. Garrett A. Wollman, August 1998