my $b;
   my $sql            = qq{SELECT b FROM blah WHERE user = ?};
   my $sth            = $dbh->prepare("$sql");
      $sth           -> execute("bahbah");
      $sth           -> bind_col(1,\$b);
   while( $sth->fetchall_arrayref ) {
      print "$b\n"    if $_;
   }