MySQL和PHP,mysqli_num_rows总是返回0

Question

我有一个问题,我似乎无法用我的注册脚本解决.

这是脚本:

<?php

    //MySQLi connection

    $con = mysqli_connect("-","-","-","users");

    if (mysqli_connect_errno())

    {

    echo "MySQLi Connection was not established: " . mysqli_connect_error();

    }

    //Reading the userdata from the registerp.php page

    $usr = mysqli_real_escape_string($con,$_POST['username']);

    $email = mysqli_real_escape_string($con,$_POST['email']);

    $pass_unhashed = mysqli_real_escape_string($con,$_POST['pass']);

    $pass = password_hash($pass_unhashed, PASSWORD_DEFAULT);

    //Checking if user exists

    $check_usr = mysqli_query($con,"SELECT * FROM users WHERE user_name = '$usr'");
    if(check_usr === false)
    {
        echo(mysqli_error($con));
    }
    else
    {
        if (mysqli_num_rows($con,$check_usr)>=1)
        {
            echo "This Username already exists";
        }
        else
        {
            echo "This Username is available";
        echo "      Name:  $usr";
        }
    }
    ?>

我的问题是我无法使验证工作(因此他们无法创建两个具有相同名称的帐户).

mysqli_num_rows即使我的表中有我的测试用户(nevondrax),也总是返回0("此用户名可用")

此外,它似乎也没有给我任何错误..

我做错了什么/我能做些什么来解决它？

Answer 1

mysqli_num_rows()接受结果集(mysqli_query()或mysqli_store_result()或mysqli_use_result())的单个参数,所以它应该是,

mysqli_num_rows($check_usr);

参考:http://php.net/manual/en/mysqli-result.num-rows.php