php - OOP PDO 查询空

Question

<?php
class User {
  private $conn;
  private $table_name = "users";

  public $id;
  public $firstname;

  public function __construct($db){
      $this->conn = $db;
  }

   public function create(){
     $query = "INSERT INTO
              " . $this->table_name . "
              SET
              firstname = :firstname";

        $stmt = $this->conn->query($query);

        $this->firstname=htmlspecialchars(strip_tags($this->firstname));

        $stmt->bindParam(':firstname', $this->firstname);

        if($stmt->execute()){
          return true;
        }else {
          $this->showError($stmt);
          return false;
        }
    }
}

Uncaught Error: Call to a member function query() on null

Why my query is NULL?

---

当我创建 var_dump 来使用时，一切顺利，但我不明白为什么我的查询为空

Answer 1

你正在运行

$stmt = $this->conn->query($query);

这是不正确的，并且会失败，因为查询具有可绑定(bind)参数，即 firstname = :firstname

你必须运行

Prepare
bindParam
execute

按照这个顺序

还有这个查询

$query = "INSERT INTO" . $this->table_name . "
            SET firstname = :firstname";

当它运行时，会将该表中每一行中的firstname更改为$this->firstname中的内容

目前尚不清楚您是否实际在其中或 $conn 属性中设置了值。