Hi Jenny1990, it's hard to follow what you are trying to do. Can you please post a stripped-down version of your code?

You probably need to build up a hash data structure. You could either do a complex SQL query on several tables, or you could build up your data structure as you read the rows from each table.

Your data might look like this after you've built it:

my $measurements = { 
                    'MeasurementA' => {
                                       1 => {
                                             'Date'  => 'DateA',
                                             'Value' => '1A',
                                            },  
                                      },  
                    'MeasurementB' => {
                                       1 => {
                                             'Date'  => 'DateB',
                                             'Value' => '3A',
                                            },  
                                       2 => {
                                             'Date'  => 'DateD',
                                             'Value' => '2A',
                                            },  
                                       3 => {
                                             'Date'  => 'DateE',
                                             'Value' => '5A',
                                            },  
                                      },  
                    'MeasurementC' => {
                                       1 => {
                                             'Date'  => 'DateC',
                                             'Value' => '3A',
                                            },  
                                      },  
                   };
[download]

And then you can use it to produce your report:

foreach my $measurement ( sort keys %{ $measurements } ) { 
  print "Measurement: $measurement\n";
  foreach my $try ( sort keys %{ $measurements->{ $measurement } } ) {
+ 
    print "  Try: $try\n";
    print "    Date:  $measurements->{ $measurement }->{ $try }->{'Dat
+e'}\n";
    print "    Value: $measurements->{ $measurement }->{ $try }->{'Val
+ue'}\n";
  }
}
[download]

Outputs:

Measurement: MeasurementA
  Try: 1
    Date:  DateA
    Value: 1A
Measurement: MeasurementB
  Try: 1
    Date:  DateB
    Value: 3A
  Try: 2
    Date:  DateD
    Value: 2A
  Try: 3
    Date:  DateE
    Value: 5A
Measurement: MeasurementC
  Try: 1
    Date:  DateC
    Value: 3A
[download]

Or,

foreach my $measurement ( sort keys %{ $measurements } ) { 
  print "$measurement -- ";
  foreach my $try ( sort keys %{ $measurements->{ $measurement } } ) {
+ 
    print "$measurements->{ $measurement }->{ $try }->{'Date'}: $measu
+rements->{ $measurement }->{ $try }->{'Value'} ";
    last if $try == scalar keys %{ $measurements->{ $measurement } };
    print " -- ";
  }
  print "\n";
}
[download]

Outputs:

MeasurementA -- DateA: 1A 
MeasurementB -- DateB: 3A  -- DateD: 2A  -- DateE: 5A 
MeasurementC -- DateC: 3A
[download]

But first you'll have to build your data structure.