my %G; { local $_ = 'G%'; $str->bind_param( 1, SQL_VARCHAR ); $str->execute(); my( $label, $num ); $str->bind_column( undef, \$label, \$num ); while ( $str->fetch() ) { my $lbl = $label; $lbl =~ s/^G/F/; $G{$lbl}++; } } { local $_ = 'F%'; $str->bind_param( 1, SQL_VARCHAR ); $str->execute(); my( $label, $num ); $str->bind_column( undef, \$label, \$num ); while ( $str->fetch() ) { print "$label $num\n" unless exists $G{$label}; } }