没有查询结果

Question

我想显示登录我网站的人的名字。这是我的login.php文件的代码，该文件包含在我网站的一个页面中。

<?php

$connect = mysql_connect("localhost","root","") or die("Error");
mysql_select_db("jpnv_db") or die("Couldn't find db");

function login() {
    $username = $_POST['username'];
    $password = $_POST['password'];

    $query = mysql_query("SELECT * FROM customers WHERE `username`='$username' AND `password`='$password'");
    $names = mysql_query("SELECT contactFirstName FROM customers WHERE `username`='$username'");

    if (empty($username)) {
        $errors[] = 'Please fill in your username. <a href="index.php">Click here to try again.</a>';
    }

    if (empty($password)) {
        $errors[] = 'Please fill in your password. <a href="index.php">Click here to try again.</a>';
    }    

    if ($errors==true) {
        foreach ($errors as $error) {
            echo $error.'<br />';
        }
    } else {
        if (mysql_num_rows($query)==true) {
            echo $names['customers'];
        } else {
            echo 'Your username and/or password are incorrect. <a href="index.php">Click here to try again.</a>';
        }
    }
}
?>

这是密码错误时的结果：

这是我实际登录成功的结果：

正如您在我的代码中所看到的，它实际上应该显示在顶部栏中登录的人的姓名。但是，它完全是空的。我在这里做错了什么？

Answer 1

您永远不会从查询中获取结果，您需要从查询中请求正确的列名称：

if (mysql_num_rows($query)==true) {
    $name = mysql_fetch_assoc($names)
    echo $name['contactFirstName']; // change the column name here
} else {...

You need to prevent SQL Injection或某人会使您的所有数据都消失。

请stop using mysql_* functions。它们不再被维护，而是officially deprecated。请改为了解prepared statements，并使用PDO。

Answer 2

function login() {

    $username = $_POST['username'];
    $password = $_POST['password'];

    if (empty($username) || empty($password))
    {
      echo "You haven't filled username/password";
      // redirect code here//
    }
    else
    {

    $query = mysqli_query("$con, SELECT * FROM customers WHERE `username`='$username' AND `password`='$password'");
         if ($query && mysqli_num_rows($query)!=0) {
         $row =mysqli_fetch_assoc($query);
         echo "Customer name is : " . $row['customers']; // you need to specify columns in between  ' ' to get it. Change it based on your need.
     }
   }
 }

注意：您应该迁移到 Mysqli 或 PDO 。代码中的$con是保存数据库连接的变量。

Answer 3

检查这行代码。您没有识别$ name变量。

else {
  //$names variable 
    if $(mysql_num_rows($query)==true) {
      $names = mysql_fetch_all($query);
        echo $names['customers'];
    } else {
        echo 'Your username and/or password are incorrect. <a href="index.php">Click here to try again.</a>';
    }
}