$db3->{RaiseError}=0;
    	unless ($sth_minus = $db3->prepare_cached("
											SELECT $column_list FROM $database_user_1.$table_names_r->[0]".'@'."$config{database_dblink_1}
											MINUS
											SELECT $column_list FROM $database_user_2.$table_names_r->[0]".'@'."$config{database_dblink_2}
										 "))
			   {warn $@ if $@;}