如何在PHP OOP中爲mysqli_num_rows創建用戶定義的函數？

Question

我盡我所能，自己找出結果，但都失敗了。

這裏是我嘗試過的最好的源代碼。

<?php 

class DataBase 
{ 
    private $connect; 
    private $dbUser; 
    private $dbHost; 
    private $dbPassword; 
    private $dbDatabase; 
    private $numRows; 
    private $results; 

    public function connect($host, $username, $pass, $db) 
    { 
     $this->dbHost = $host; 
     $this->dbUser = $username; 
     $this->dbPassword = $pass; 
     $this->dbDatabase = $db; 

     return $this->connect = mysqli_connect($this->dbHost, $this->dbUser, $this->dbPassword, $this->dbDatabase); 
    } 

    public function disConnect($connect) { 
     return mysqli_close($this->connect = $connect); 
    } 

    public function select($table, $where = array(), $orderBy = NULL) { 
     if (count($where) === 3) { 
      $operators = array('=', '<', '>', '>=', '<=', 'LIKE'); 

      $field = $where[0]; 
      $operator = $where[1]; 
      $value = $where[2]; 

      if (in_array($operator, $operators)) { 
       $query = "SELECT * FROM {$table} WHERE '". $field . $operator . $value . "'"; 
      } 

      if (mysqli_query($this->connect, $query)) { 
       return true; 
      } else { 
       die(mysqli_error($this->connect)); 
      } 
     } 
    } 

    public function countRows($queryRes) 
    { 
     if (mysqli_num_rows($queryRes) > 0) { 
      return true; 
     } else { 
      return false; 
     } 
    } 
} 

我得到的錯誤：

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\wamp\www\Practice\index.php on line 70

和線路70：if (mysqli_num_rows($queryRes) > 0) {

這裏就是我如何調用該方法：

$suc = ""; 
if (isset($_POST['btnSubmit'])) { 
    $con = new DataBase(); 
    $objDb = $con->connect('localhost', 'root', '', 'practice'); 

    $username = $_POST["username"]; 

    $suc = $con->select('users', ['username', 'LIKE', '%'.$username.'%']); 

    if ($suc) { 
     print_r($con->countRows($suc)); 
    } else { 
     echo "Unable to Find Record !"; 
    } 
    //print_r($suc); 

    $con->disConnect($objDb); 
} 
?> 

請指引我我在哪裏犯錯誤。

感謝

Answer 1

你有$numRows類屬性。你爲什麼不使用它？

將查詢行數設置爲$this->numRows屬性。

更改select()方法：

public function select($table, $where = array(), $orderBy = NULL) { 
     if (count($where) === 3) { 
      $operators = array('=', '<', '>', '>=', '<=', 'LIKE'); 

      $field = $where[0]; 
      $operator = $where[1]; 
      $value = $where[2]; 

      if (in_array($operator, $operators)) { 
       $query = "SELECT * FROM {$table} WHERE '". $field . $operator . $value . "'"; 
      } 
      $result = mysqli_query($this->connect, $query); 

      if ($result) { 
       $this->numRows = mysqli_num_rows($result); 
       return true; 
      } else { 
       die(mysqli_error($this->connect)); 
      } 
     } 
    } 

，改變你的countRows()方法類似yhis：你是如何調用countRows

public function countRows($queryRes) 
     { 
      return $this->numRows == 0 ? false : true; 
     } 

Answer 2

function countRows($sql) 
{ 
    $rst    = @mysql_query($sql)or trigger_error("SQxxxL", E_USER_ERROR); 
    return $numrows  = mysql_num_rows($rst); 
}