eval {      ### Catch _any_ kind of failures from the code within

    ### Enable auto-error checking on the database handle
    $dbh->{RaiseError} = 1;

    ### Prepare a SQL statement for execution
    my $sth = $dbh->prepare( "select distinct `FID_CUST` from `session` where `DAT_END` between `$key` and `$hash{$key}`" );

    while (1) {
	### Execute the statement in the database
	$sth->execute();

	### Retrieve the returned rows of data
	while ( my @row = $sth->fetchrow_array() ) {
	    print "Row: @row\n";
	}
    }
};
warn "Monitoring aborted by error: $@\n" if $@;