php - 如何使用从一个类到另一个类的连接

Question

class Database {

    public $isConn;
    private static $_instance = null;
    private $datab;

    // connect to db
    public function __construct($username = "root", $password = "", $host = "localhost", $dbname = "market", $options = []) {
        $this->isConn = TRUE;
        try {
            $this->datab = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
            $this->datab->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $this->datab->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
        } catch (PDOException $e) {
            throw new Exception($e->getMessage());
        }
    }

    public static function getInstance() {
        if (!isset(self::$_instance)) {
            self::$_instance = new Database();
        }
        return self::$_instance;
    }

现在在每个需要数据库连接的类中

class test {

    private $_db = null;

    public function __construct() {
        $this->_db = Database::getInstance();
    }

    public function test(){
       return $this->_db->getRow("SELECT * FROM users", PDO::FETCH_ASSOC, []);
    }

   public static function testStatic(){
        return $this->_db->getRow("SELECT * FROM users", PDO::FETCH_ASSOC, []);
        }

现在它给我一个错误说不能使用 $this，那么我如何使用 self::来使用它？

现在如何在静态函数和非静态函数中一起使用它

Answer 1

在需要时获取数据库实例。

class test {

    public function test(){
       return Database::getInstance()->getRow("SELECT * FROM users", PDO::FETCH_ASSOC, []);
    }

   public static function testStatic(){
        return Database::getInstance()->getRow("SELECT * FROM users", PDO::FETCH_ASSOC, []);
    }
}