And now, rather than declaring and preparing the queries once per array element, you can lift them outside the loops:

my $sth = $db->prepare("SELECT curr_parent_id FROM demstock2 WHERE ds_
+id=?");
my $move_sth = $db->prepare("UPDATE demstock2 SET curr_parent_id=? WHE
+RE ds_id=?");
my $action_sth = $db->prepare("
INSERT INTO action
(action_id, action_type, ds_id, occurred,          ref_no,  staff_id) 
+VALUES
(NULL,      'MOVE',      ?,     CURRENT_TIMESTAMP, ?, ?)");
for my $child (@built, @acc) {
  #Find out if it still is in free stock
  $sth->execute($child) or ...
  my $current_status = $sth->fetchrow_hashref;
  if($current_status->{"curr_parent_id"} != 0) {
    print ...;
    next;
  }
  $move_sth->execute($main, $child) or ...
  $action_sth->execute($child, "0,$main", $caluser) or ...;
}
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That's why placeholders rock :-)

--
Tommy
Too stupid to live.
Too stubborn to die.