致命错误：调用未定义的方法 Database::query()

Question

我在这部分的某处有一个错误（**Fatal Error : Call to undefined method Database::query()**），我不知道这是从哪里来的。因为我只是改变了我的构造函数

Class Database{

public function __construct(){

    $this->getConn();
}
public function getConn(){
    return new mysqli("localhost", "root", "", "os_db");
}
public function select($query){
    $data = array();
    if($result = $this->query($query)){
        while($row = $result->fetch_assoc()){
            $data[] = $row;
        }
    }else{
        $data = array();
    }
return $data;
}
}

如果我将查询更改为if($result = $this->getConn()->query($query).. 它可以完美运行.. 无论如何我必须调用连接我会这样做$this->query($query)

Answer 1

Class Database {

  public function __construct() {

    $this->getConn(); 

  } 

  public function getConn() { 

    $db = new mysqli("localhost", "root", "", "os_db"); 
    $this->db = $db;

  } 

  public function select($query) { 

    $data = array(); 

    if($result = $this->db->query($query)){ 

      while($row = $result->fetch_assoc()){ 

        $data[] = $row; 

      } 

    } else { 

      $data = array(); 

    } 

    return $data;

  }

}

或者不是每次调用类时都连接，您可以执行以下操作：

Class Database {

  public function __construct() {

  } 

  public function getConn() { 

    $db = new mysqli("localhost", "root", "", "os_db"); 
    $this->db = $db;

  } 

  public function select($query) { 

    $this->getConn();

    $data = array(); 

    if($result = $this->db->query($query)){ 

      while($row = $result->fetch_assoc()){ 

        $data[] = $row; 

      } 

    } else { 

      $data = array(); 

    } 

    return $data;

  }

}