MYSQLi num_rows總是返回0

Question

我還是PHP和MySQL中的新手。我在幾天之前開始學習MySQLi，並遇到了這個問題。 此頁面被命名爲login.php。問題是查詢返回0個num行。 當我在phpmyadmin中運行查詢時，它顯示此消息和1行。

顯示行0 - 0（1個總計，查詢花費0.0010秒）

圖片：

這是我的代碼：

<?php 
session_start(); 
require 'config.php'; 
$username = $_POST['username']; 
$password = $_POST['password']; 
$salt = 'qwerty'; 
$pass_prepare = md5($salt).sha1($password); 

if ($_SERVER['REQUEST_METHOD'] != "POST") { 
    header('Location: index.php'); 
} 
if (isset($username) && isset($pass_prepare)) { 
    $stmt = mysqli_prepare($db_con, "SELECT user_id, username, password, rank, last_activity FROM imes_users WHERE username=? AND password=? LIMIT 1"); 
    mysqli_stmt_bind_param($stmt, "ss", $username, $pass_prepare); 
    mysqli_execute($stmt); 
    mysqli_stmt_bind_result($stmt, $user_id, $username1, $password1, $rank, $last_activity); 
    mysqli_stmt_fetch($stmt); 
    echo mysqli_num_rows($stmt); 
} else { 
    echo 'error'; 
} 

莫非你幫我解決這個問題？

Answer 1

$sql = mysqli_query($connection, $query); 
$count = $sql->num_rows; // $count contains now your value 

Answer 2

您正在使用預處理語句，因此語法稍有不同。您想使用mysqli_stmt_num_rows而不是mysqli_num_rows。

$stmt = mysqli_prepare($db_con, "SELECT user_id, username, password, rank, last_activity FROM imes_users WHERE username=? AND password=? LIMIT 1"); 
mysqli_stmt_bind_param($stmt, "ss", $username, $pass_prepare); 
mysqli_execute($stmt); 
mysqli_stmt_bind_result($stmt, $user_id, $username1, $password1, $rank, $last_activity); 
mysqli_stmt_fetch($stmt); 
echo mysqli_stmt_num_rows($stmt);