Account	Entity	Unit	Jan	Feb	Mar
Account01	Entity01	Unit01	1	2	3
Account01	Entity01	Unit01	4	5	6
Account01	Entity01	Unit01	7	8	9
Account02	Entity02	Unit02	10	11	12

##</code><code>##

Account	Entity	Unit	Jan	Feb	Mar
Account01	Entity01	Unit01	12	15	18
Account02	Entity02	Unit02	10	11	12

##</code><code>##

CREATE TABLE concat_FRA3 AS
  SELECT Account, Entity, Unit, 
	SUM(Jan) Jan,
	SUM(Feb) Feb,
	SUM(Mar) Mar
  FROM concat_FRA2
  GROUP BY Account, Entity, Unit;

##</code><code>##

# Store
my %storage;
foreach my $row (@$result_set) {
    my $hash_key = encode_hash_key(row);
    my $new_row = $row;
    if (exists $storage{$hash_key}) {
        $new_row = merge_rows($row, $storage{$hash_key});
    }
    $storage{$hash_key} = $new_row;
}