{
my $sth;

sub _read_from_db {
    my ($array_ref) = @_;

    if (not defined $sth) {
        $sql = qq/ ... /;
        $sth = $dbh->prepare( $sql );
    }
    $sth->bind_param( ... );
    $sth->execute();
   
    @$array_ref = $sth->fetchrow_array();    
} 
}