By 'later use' do you mean later in the script or later in an entirely dseparate session?

In any case, you want something like:

use strict;
use DBI;

#
# ... connect to DB, execute the SELECT
# statement to the statement handle $sth...
#

# This method is slower than selecting an 
# arrayref, but it has the benefit of being
# easy to understand

# 'KEY_FIELD' is the name of your key field,
# 'DATA_FIELD' is the name of the data field
# you want to save

my %records = ();
while ( my $row = $sth->fetchrow_hashref ) {
  $records{ $row->{'KEY_FIELD'} } = $row->{'DATA_FIELD'};
}

# You can now do anything you want with
# %records and use the information without
# dealing with the database.

# ...later...

print "Records retrieved:\n";
while ( my ( $key, $value ) = each %records ) {
  print "$key --> $value\n";
}
[download]

Hope this helps, Chris