use DBM::Deep;

my $dbh = get_dbh();

# This is the magic. :-)
my $db = DBM::Deep->new( 'db_file.db' );

my @keys = 
    qw(employee_id firstname lastname title dept salary date_hired);
my @values = @{$dbh->selectall_arrayref($query)};

for my $v (@values){
    my @vals = @$v; # one ID per array
    for (@vals){
        $_ = '-' unless $_; # in case of empty fields
    }

    # Map is a wonderful piece of magic. Look really really hard at
    # this code before freaking out.
    $db->{$vals[0]} = {
        (map {
            $keys[$_] => $vals[$_];
        } 0 .. $#keys)
    };
}