my $sth = $dbh->prepare("
                      INSERT INTO web_sessions_aux 
                      (wsa_id, wsa_type, wsa_key, wsa_value)
                      VALUES (?,?,?,?)");

foreach my $key (keys %$pairs) {
     my $key_value = defined($pairs->{$key})?
                             $pairs->{$key} : '';

     $sth->execute($id,$type,$key,$key_value);
}