全局变量在php类中不起作用

为什么插入函数中的$connect不起作用？ 我在$connect之前添加了全局，但仍然不起作用。

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这是一个非常简单的MySQL类。

您的语法不正确

改变这个,

class Database
{
    public $connect = "";

    public function connect()
    {
       $connect = new mysqli("localhost", "root", "1521", "phone");
       ini_set('default_charset', "UTF-8");
       mysqli_set_charset($connect, "utf8");
       header('Content-type: text/html; charset=UTF-8');
       if ($connect->connect_error) {
           die('Not connect' . mysqli_connect_error());
       }
    }

    public function insert()
    {
        $sql = "SELECT id FROM personal ORDER BY id DESC LIMIT 1";
        //global $connect;
        $result = $connect->query($sql);//// this here !!!!!!!!
        $row = $result->fetch_assoc();
        $tempint = (int)$row['id'];
        $tempint += 1;
    }
}

对,

而且

对,

通过上述更改，它应该可以解决问题

$connect已在类的作用域中创建，因此当您引用它时，需要使用$this

$connect = new mysqli("localhost", "root", "1521", "phone");

$this->connect = new mysqli("localhost", "root", "1521", "phone");

$result = $connect->query($sql);

$result = $this->connect->query($sql);