Just traverse your entire set of tuples, keeping track of all values of feature and/or plan. Then traverse each feature, and each plan, and output either the value you stored, or a useful default. (If you have a truly vast number of features and/or plans, it might be worthwhile to do two passes so you don't have to keep all of them in memory at once, but that seems unlikely...)

my %features;
my %plans;
my %feat_plan_val;
while ( my ( $feat_id, $feat_name,
             $plan_id, $plan_name,
             $val ) = $sth->fetchrow_array() )
{
    $features{$feat_id} = $feature_name;
    $plans{$plan_id} = $plan_name;
    $feat_plan_val{$feat_id}{$plan_id} = $val;
}

# later...

my @plan_ids = sort keys %plans;
print join( "\t", 'Features', @plans{@plan_ids} ), "\n";
foreach my $feat_id ( sort keys %features )
{
    my @vals = ( $features{$feat_id} );
    foreach my $plan_id ( @plan_ids )
    {
        my $val = $feat_plan_val{$feat_id}{$plan_id};
        push @vals, ( defined $val ? $val : '-' );
    }
    print join( "\t", @vals ), "\n";
}
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It sounds like you've started coding without thinking about the design, and frankly, it sounds like you would benefit from more than just "an idea" now that you are stuck.

But in the spirit of careful-what-you-wish-for, here's an idea:

Add a column "plan_id" to your plan table, this will link to tables described below.

Make a third table called "features", and include these columns

• feature_id
• feature_name

Make a fourth table called "plan_features", and include these columns

• plan_id
• feature_id

The plan_features table links the plans table to the features table in a many-to-many relationship.

Make a fifth table called "feature_valid_values", and include these columns

• feature_id
• valid_value

This table contains valid values for each feature, such as "yes", "no", "unlimited". You don't need this table if you don't care what values are used for each feature.

Can you see how this hangs together? The idea is that each distinct set of information (groups, plans, features, feature values) has its own identity, and relates to other sets of information in a specific way.