PHP开发多用户商城系统的好处和原因

<?php
// 处理用户提交的注册信息
$username = $_POST['username'];
$password = $_POST['password'];

// 在数据库中创建新用户
$sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
$result = mysqli_query($conn, $sql);

// 检查是否成功插入新用户
if ($result) {
    echo "注册成功！";
} else {
    echo "注册失败，请重试。";
}
?>

<form method="POST" action="register.php">
    <input type="text" name="username" placeholder="用户名">
    <br>
    <input type="password" name="password" placeholder="密码">
    <br>
    <input type="submit" value="注册">
</form>

<?php
// 处理用户提交的登录信息
$username = $_POST['username'];
$password = $_POST['password'];

// 查询数据库中匹配的用户信息
$sql = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($conn, $sql);

// 检查是否查询到匹配的用户
if (mysqli_num_rows($result) > 0) {
    echo "登录成功！";
} else {
    echo "用户名或密码错误，请重试。";
}
?>

<form method="POST" action="login.php">
    <input type="text" name="username" placeholder="用户名">
    <br>
    <input type="password" name="password" placeholder="密码">
    <br>
    <input type="submit" value="登录">
</form>