When running the article classification function, it prompts that the database PDO preprocessing operation failed.

Question

public function query($sql,$batch=false){

$data=$batch?$this->data:array($this->data);

      $this->data=array();

                                                          using   using preprocessing method             ’ ’ ’ ’ ’ s ’ using db->t db-----

foreach($data as $v){

if($stmt->execute($v)===false){

die("Database PDO Preprocessing operation failed");

                                                                                                                                                                                .