my $pull1 = "SELECT id, seq from table";
my $pull2 = "SELECT id, seq from table where table.id in(long string of nested "in" criteria);
my $sql1 = $lib_dbh->selectall_arrayref($pull1);
my $sql2 = $lib_dbh->selectall_arrayref($pull2);

foreach my $sql1 (@{$sql1}) {
    $table1{$sql1->[1]}{$sql1->[0]}=undef;  
}

foreach my $sql2 (@{$sql2}) {                
    $table2{$sql2->[1]}{$sql2->[0]}=undef;  
}

my @bases = ('A','C','G','T');

Label: foreach my $x (keys %table1){    

    if (exists $table2 ({$x})) {

my $found_alt = 0;

my @storage_array = ();
	@{$storage_array[1]} =  keys %{$table1{$x}}; 

foreach my $bases (@bases) {
        my $alt = $x;
        substr($alt, 6, 1) = $opt;
        next if ($alt eq $x);
        if (exists $table1{$alt}) {
            $found_alt = 1;
            push @{$storage_array[2]}, keys %{$table1{$alt}};
		}
	}


	next Label unless ($found_alt );  #continues to follow on script.