如何修复“Warning:mysqli_stmt::bind_param():类型定义字符串中的元素数与绑定变量数不匹配”[重复]

有4个 ? 在您的查询中,如果 id 列是自动递增的,您可以将其从查询中删除,如下所示:

    public function createUserAccount($username,$password,$department){
        if($this->userExists($username)){
            return "USER_ALREADY_EXISTS";
        }
        else{
            $pass_hash = password_hash($password,PASSWORD_BCRYPT,["cost"=>8]);
            $pre_stmt = $this->con->prepare("INSERT INTO `user`(`username`, `password`, `department`) VALUES (?,?,?)");
            $pre_stmt->bind_param("sss", $username, $pass_hash, $department);
            $result = $pre_stmt->execute() or die($this->con->error);
            if($result){
                return $this->con->insert_id;
            }
            else{
                return "some error";
            }
        }