$sth = $dbh->prepare("select a, b, c from foo");
$sth->execute;
while($row = $sth->fetch) {
    # $row->[0] is column 'a'
    # $row->[1] is column 'b', 
    # etc...
}
[download]

while(($one, $two, $three) = $sth->fetchrow_array) {
    # $one, $two and $three are columns a, b and c
}
[download]