Mysqli num_rows（）返回未定义的属性

Question

I'm trying to count up the amount of registered users in my database however, I am having a problem with the num_rows.. as its giving an error.

Here is my index.php code:

<?php
require 'connections.php';
$con->query("SELECT users, UserID from users");
$totalplayers = $con->num_rows;
?>

Here is my connections.php:

<?php
ob_start();
session_start();
$con = mysqli_connect("localhost", "root", "", "website");

if (isset($_SESSION['UserID'])) {
    $result = $con->query("select * from users where UserID=".$_SESSION['UserID']);
    $row = $result->fetch_assoc();

However, it is giving this error and I have no clue what to do!:

Notice: Undefined property: mysqli::$num_rows in C:....\\index.php on line 4

Answer 1

you should assign the result of the query and then get the count :

<?php
require 'connections.php';
$result = $con->query("SELECT users, UserID from users");
// $result is a mysqli_stmt
$totalplayers = $result->num_rows;
?>

Reference: http://php.net/manual/en/mysqli-stmt.num-rows.php