Thank you everyone for your replys - they were very helpfull, but did not solve my problem!!!
Here's a little more detailed explanation:

I need to read a file (line by line of course).
Line looks like that "subject^email^timestamp"

After file is read I need to do Insertion into database. Now, subjects could be the same and I decided to create this datastructure:
%subjects{$subject}{%hash => email, timestamp} (hope it's clear so far)
%subjects is hash, which has "subject" as a key
$subject is array, which holds hashes or emails and times

So, I created this code:

my %subjects;

foreach my $subm(@subm){
        ($subject, $email, $time) = split(/^/, $subm);


        my %info;
        $info{email} = $email;
        $info{time} = $time;

        if(! exists $subjects{$subject}){
                print "Key DOES NOT exist\n";
                $subjects{$subject} = [];
        }else{
                print "KEY DO EXIST\n";
        }

        push @{$subjects{$subject}}, %info;

}
[download]

I have this code to check that everything is correct:

foreach my $key (sort (keys %subjects)){

        print "\n\nKEY = $key";
        my @ar = @{subjects{$key}};
        my $size = @ar;
        print "\nSize of Array = $size";
}
[download]

Unfortunately, Size gives me size =1 , which is not true. Please tell me if I am doing something wrong....

Thank you very much!!!

code tags by holli