my $sth = $dbh->prepare("Select a, b from t1") or die "...";
$sth->execute or die "...";
while (my $row = $sth->fetchrow_arrayref) {
   my $cursor = $dbh->prepare("select d, e from t2 where k = ?");
   $cursor->execute($row->[1]); # t1.b
   ....
}

##</code><code>##

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:Wq
Not an editor command: Wq