The errors disappear for me when I use all lower-case for the "sub" keyword (not "Sub") and when I declare your variables with my in the RowCount sub:

sub Fetch
{

    my $class = shift;
    my $sql = $class->{SQL};
    #return $sql->fetchrow_array();
}

sub RowCount
{

    my $class = shift;
    my $sql = $class->{SQL};
    return $sql->rows;
}
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My text editor with syntax highlighting clearly showed the Sub as not being a keyword.