Question

我在我的数据库类

中以这种方式讨论$ db对象

class db{
private $connection;

public function __construct(){
    $this->connect();
    }
public function connect(){
    $this->connection=mysqli_connect('localhost','root','','new5');
    }
   }
        $db=new db;

我在另一个类（配置文件类）中将此$ db对象用作链接标识符

   $query=$db->query("SELECT id, parent_id, name FROM categories_general");

请帮助我，我怎样才能摆脱这个错误。实际上我最近从mysql转移到了mysqli。

Answer 1

试

$db = mysqli_connect('localhost','root','XXX','XXX');

Answer 2

$db = new mysqli('localhost','root','','test');
$sql = "select * from user";
$result = $db->query($sql);
var_dump($result->fetch_assoc());

Answer 3

你正在使用mysqli的程序风格。所以你必须在db class中创建查询方法。

class db{
  private $connection;

  public function __construct(){
    $this->connect();
  }
  public function connect(){
    $this->connection=mysqli_connect('localhost','root','','new5');
  }
  //add these methods
  public function query($query_string){
    return mysqli_query($this->connection, $query_string);
  }
  public function fetch_row($mysqli_result){
    return mysqli_fetch_row($this->connection, $mysqli_result);
  }
  //and other functions you need
}

或者您可以使用extends方法使用面向对象的样式;

class db extends mysqli{
  function __construct($host, $username, $password, $databaseName, $port=3306){
    mysqli::__construct($host, $username, $password, $databaseName, $port);
  }
}

Answer 4

添加功能

public function getDB()
{
    return $this->_mysql;
}

 $query=mysqli_query($db->getDB(),"SELECT id, parent_id, name FROM categories_general");

致命错误：调用未定义的函数mysqli（）

4 个答案: