NAME

DBIx::Lookup::Field - Create a lookup hash from a database table

VERSION

version 2.101420

SYNOPSIS

  use DBI;
  use DBIx::Lookup::Field qw(dbi_lookup_field);

  my $dbh = DBI->connect('...', '...', '...');
  my $inst_id = dbi_lookup_field(
      DBH   => $dbh,
      TABLE => 'institution',
      KEY   => 'name',
      VALUE => 'id',
  );

  print "Inst_A has id ", $inst_id->{Inst_A};

DESCRIPTION

This module provides a way to construct a hash from a database table. This is useful for the situation where you have to perform many lookups of a field by using a key from the same table. If, for example, a table has an id field and a name field and you often have to look up the name by its id, it might be wasteful to issue many separate SQL queries. Having the two fields as a hash speeds up processing, although at the expense of memory.

The functions can be exported individually or with the :all tag.

FUNCTIONS

dbi_lookup_field()

This function creates a hash from two fields in a database table on a DBI connection. One field acts as the hash key, the other acts as the hash value. It expects a parameter hash and returns a reference to the lookup hash.

The following parameters are accepted. Parameters can be required or optional. If a required parameter isn't given, an exception is raised (i.e., it dies).

DBH

The database handle through which to access the table from which to create the lookup. Required.

TABLE

The name of the table that contains the key and value fields. Required.

KEY

The field name of the field that is to act as the hash key. Required.

VALUE

The field name of the field that is to act as the hash value. Required.

WHERE

A SQL 'WHERE' clause with which to restrict the 'SELECT' statement that is used to create the hash. Optional.

dbi_lookup_field_with_reverse()

This function takes the same parameters as dbi_lookup_field() but in addition to the lookup hash, it also returns a reversed hash where you can lookup the table keys by the table values.

  my ($lookup, $reverse) = dbi_lookup_field_with_reverse(...);

Note that if a value occurs more than once, only one of the potential keys will win (the one that occurs first in the lookup hash's key order), so be warned.

INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=DBIx-Lookup-Field.

AVAILABILITY

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit http://www.perl.com/CPAN/ to find a CPAN site near you, or see http://search.cpan.org/dist/DBIx-Lookup-Field/.

The development version lives at http://github.com/hanekomu/DBIx-Lookup-Field/. Instead of sending patches, please fork this project using the standard git and github infrastructure.

AUTHOR

  Marcel Gruenauer <marcel@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2001 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

cpanm DBIx::Lookup::Field

perl -MCPAN -e shell
install DBIx::Lookup::Field