如何在PHP中該類的另一個函數內調用同一類的函數

Question

當我在showAll內調用函數connect和closeDb時，出現錯誤。

class DBConnect {

private $con;

private function connect() {

    $con = mysql_connect("localhost", "root", "");
    mysql_select_db('school');
}

private function closeDb() {
    mysql_close($this->con);
}

public function showAll() {
    self::connect();

    echo "THis is from the showAll method";
    self::closeDb();
}

}

Answer 1

Mysql擴展在PHP 5.5.0中已棄用，在PHP 7.0.0中已刪除。 相反，應使用MySQLi或PDO_MySQL擴展。

了解面向對象編程的基礎知識： http : //php.net/manual/zh/language.oop5.php

Answer 2

這條線看起來是錯誤的。 $con = mysql_connect("localhost", "root", "");

如果想做$this->con = mysql_connect("localhost", "root", "");

然后

public function showAll() { $this->connect(); echo "THis is from the showAll method"; $this->closeDb(); } public function showAll() { $this->connect(); echo "THis is from the showAll method"; $this->closeDb(); } 使用$ this！