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How to develop a basic user login function using PHP

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Release： 2023-09-25 09:02:02

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How to develop a basic user login function using PHP

How to use PHP to develop a basic user login function

PHP is a powerful server-side scripting language that is widely used in web development. In web applications, user login functionality is a common requirement. This article will show you how to use PHP to develop a basic user login function, as well as specific code examples.

1. Create database and user table

First, we need to create a table in the MySQL database to store user information. You can create a table named "users" using the following SQL statement:

CREATE TABLE users (
  id INT(11) AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(50) NOT NULL,
  password VARCHAR(255) NOT NULL
);

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This table has three fields: id, username, and password. The id field is an auto-incrementing primary key used to uniquely identify each user. The username and password fields are used to store username and password respectively.

2. Create a login page

Next, we need to create a login page to allow users to enter their username and password. Create a file called "login.php" using the following code:

<!DOCTYPE html>
<html>
<head>
  <title>用户登录</title>
</head>
<body>
  <h2>用户登录</h2>
  <form action="login.php" method="POST">
    <label for="username">用户名：</label>
    <input type="text" name="username" id="username" required><br>
    <label for="password">密码：</label>
    <input type="password" name="password" id="password" required><br>
    <input type="submit" value="登录">
  </form>
</body>
</html>

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This page contains a form to submit the username and password via the POST method to the same page (i.e. "login.php"). The input element in the form is used to enter the username and password, and a submit button is used to submit the form.

3. Verify user input and log in

At the beginning of the "login.php" file, we need to add the following code to connect to the database:

$dbHost = 'localhost';
$dbUsername = 'your_username';
$dbPassword = 'your_password';
$dbName = 'your_database';

$conn = new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);

if ($conn->connect_error) {
  die("数据库连接失败：" . $conn->connect_error);
}

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Please replace # Replace ##$dbUsername, $dbPassword, and $dbName with the actual information for your MySQL database.

Next, we need to add the following code to the "login.php" file to verify user input and log in:

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
  $username = $_POST['username'];
  $password = $_POST['password'];

  $sql = "SELECT * FROM users WHERE username='$username'";
  $result = $conn->query($sql);

  if ($result->num_rows == 1) {
    $row = $result->fetch_assoc();
    if (password_verify($password, $row['password'])) {
      echo "登录成功！";
    } else {
      echo "密码错误！";
    }
  } else {
    echo "用户名不存在！";
  }
}

$conn->close();

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This code first obtains the username and password submitted from the form . It then queries the database to find users with matching usernames provided. If a matching user is found and the password provided matches the password stored in the database, the login is successful. Otherwise, an appropriate error message will be displayed.

4. Improve the user login function

The above code is just a basic example of the user login function. You can modify and improve it according to your own needs. The following are some possible improvements and added functions:

Use HTML and CSS to beautify the login page.
Add registration function to allow users to create new accounts on the website.
Use a hash algorithm to encrypt passwords and store them in the database for added security.
Add password reset function, allowing users to reset their password via email or SMS.

Summary

Through this article, you learned how to use PHP to develop a basic user login function. We created a database table to store user information and a login page for users to enter their username and password. We then validated the user input and logged in. Of course, we also provide some improvements and added features to meet different needs.

Hope this article helps you understand how to develop a basic user login function using PHP and provides a good starting point for your web application. Happy coding!

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