use Data::Dumper;
print GetNodes({name => "hello",type => "god", color => "greeen"});

sub GetNodes
{
    my $meta = shift;   #expects a hash of {name => value}
    print Dumper($meta);
    my $sql = "SELECT md1.node_id FROM ";
    my @From;           # list of tables
    my @Where;          # list of conditions
    my @LastWhere;
    my $i = 0;
    foreach my $name (keys %$meta)
    {
        $i ++;
        push @From, "`meta_data` as md$i";
        push @Where,"md$i.name = \"" . $name . "\"";
        push @Where,"md$i.value = \"" . $meta->{$name} . "\"";
        push @LastWhere,"md$i.node_id";
    }
    $sql .= join(",",@From) . " WHERE ";
    $sql .= join(" AND ", @Where);
    $sql .= " AND " .join(" = ",@LastWhere) . ";";
    return $sql;
}