doLogin.php:<?phpheader('content-type:text/html;charset=utf-8');$mysqli=new mysqli('localhost','root','123456','test');if($mysqli->errno){ die('Connect Error'.$mysqli->error);}$mysqli->set_charset('UTF8');$username=$_POST['username'];$password=md5($_POST['password']);$sql="SELECT * FROM user WHERE username='{$username}' AND password='{$password}'";$mysqli_result=$mysqli->query($sql);if($mysqli_result && $mysqli_result->num_rows>0){ echo '登陸成功';}else{ echo '登陸失敗';}上述代碼如果$password不用md5加密，就能正常查詢，但是查詢加密后的信息就顯示結果為空