Question

我正在编写以下代码来从表中获取一行：

$query = "SELECT  ........FROM ............WHERE........AND ID = ?";
$conn = new Connection();
$stmt = $conn->mysqli->prepare($query);
$stmt->bind_param('i', $_SESSION['id']);
$stmt->execute();
echo 'Num rows = '.$stmt->num_rows();

这是Connection（）;

的代码

define('SERVER', 'localhost');
define('USER', 'root');
define('PASS', 'xxx');
define('DB', 'xxx');

class Connection{
        var $mysqli = null;

        function __construct(){
            try{
                if(!$this->mysqli){
                    $this->mysqli = new MySQLi(SERVER, USER, PASS, DB);
                    if(!$this->mysqli)
                        throw new Exception('Could not create connection using MySQLi', 'NO_CONNECTION');
                }
            }
            catch(Exception $ex){
                echo "ERROR: ".$e->getMessage();
            }
        }
    }

如果我回显查询并在ID等于$ _SESSION ['id']的值的Navicat上运行它，它确实会返回一行。但是在网页上，它显示输出为：

Num rows = 0

代码有什么问题？ Plz注意 echo $ _SESSION ['id'] 显示值。

由于

Answer 1

使用store_result()存储结果集，然后访问$stmt->num_rows作为属性，而不是方法。（不要使用()）

$query = "SELECT  ........FROM ............WHERE........AND ID = ?";
$conn = new Connection();
$stmt = $conn->mysqli->prepare($query);
$stmt->bind_param('i', $_SESSION['id']);
$stmt->execute();

// Call store_result() before accessing num_rows()
$stmt->store_result();

// And access num_rows as a property, not a method
echo 'Num rows = '.$stmt->num_rows;

无法获取mysqli bind_param绑定变量

1 个答案: