my $sql = 'SELECT student_id, grade, instructor 
           FROM student_info_table 
           WHERE class = ? 
           ORDER BY student_id';

my $sth = $dbh->prepare_cached($sql);
$sth->execute('BUS4000');

while ( @row = $sth->fetchrow_array ) {
    my ( $id, $grade, $instructor ) = @row;
    # blah
}