html - Deleting a row using PHP but only works sometimes -

I am having trouble removing a line from the database; The connection is perfectly fine, because I tested it with other things and the variable is to delete the correct ID in $ first .

  & lt ;? Php if (isset ($ _GET ['output'])) {$ generation = $ _GET ['output']; $ Arr = Explosion (".", $ PRODUCT, 2); $ First = $ arrival [0]; $ Filename = "production / $ first.php"; Echo $ first; If (file_exists ($ filename) == true) {$ str2 = "Delete from output WHERE production_id = '$ first'"; If ($ mysqli- & gt; query ($ str2) == true) {echo "successfully removed first $"; Unlink to ($ filename); }}}? & Gt;