在PHP(PDO)中访问私有变量

问题描述

我在PHP中使用PDO ...我遇到以下问题.

I am using PDO in PHP ... I have the following problem.

以下代码不起作用.

class A {
 private $getUsersQuery = "SELECT * FROM users";
 ...
 public function getUsers() {
   $DBH = A::getDatabaseConnection();
   try {
      $query = $DBH->prepare($this->getUsersQuery);
      ...
   } catch(PDOException $e) {}
 }
}

但是如果我使用字符串，它就可以工作.

But if I use the string it works.

$DBH->prepare("SELECT * FROM users");

即使我在prepare()之外使用回显，它也可以工作...

Even if I use the echo outside the prepare() it works ...

echo $this->getUsersQuery;   // Outputs the sql string.

有人可以指出问题所在吗?

Can someone point out what the problem might be.

更新:

错误:

SQLSTATE [42000]:语法错误或访问冲突:1065查询为空

SQLSTATE[42000]: Syntax error or access violation: 1065 Query was empty

谢谢

推荐答案

如您的注释中所述，您对非静态方法进行了静态调用.

As mentionned in your comment, you make a static call to a method that is not static.

在这样调用的方法中使用$this毫无意义:

Using $this in a method that is called like this makes no sense:

$results = A::getUsers();

实例化您的类，然后在类对象上调用该方法.

Instanciate your class, and then call the method on the class object.

$a = new A();
$a->getUsers();

或将您的方法和SQL查询设为静态.

Or make your method and SQL query static.

这篇关于在PHP(PDO)中访问私有变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！