I don't see any debugging prints in there - those can really help you see what's going on. In each subroutine, just after you 'shift' the parameter(s) off of @_, print each one out just to make sure the subroutine is receiving what you think it's receiving, like:

    sub get_columns ($) {
       my $log = shift;
       ### Add this ###
       print "get_columns sub TOP: \$log = $log\n";
       my @Cols = ();
[download]

And, you should also print the sql out before each 'prepare', like:

    my $sql = "SELECT * FROM $log";
    ### Add this print ###
    print "get_columns sub just before prepare: \$sql = $sql\n";    
    $sth = $dbobject->prepare($sql);
[download]

You get the idea - just make sure you're getting everything you think you are. Post back your results.