#!/usr/bin/perl

use DBI;
use strict;

# connect to the database, using mysql in example
my $dbh = DBI->connect("DBI:mysql:dbname:hostname", "user", "pass") or die "Couldn't Connect: $DBI::errstr";

# prepare statement handle
$sth = $dbh->prepare("SELECT * FROM table WHERE field = ?);  
# ? is a placeholder that can be filled when execute is called
$sth->execute($val_of_field) or die "Error: $DBI::errstr";
# $DBI::errstr stores the error string returned by the DB

while (@vals = $sth->fetchrow->array()) {
    # do stuff
    # do more stuff
}
$sth->finish();       #close statement handle
$dbh->disconnect();   #disconnect