如何实现在线记账功能 - 使用PHP开发在线记账系统的方法

<?php
// 数据库连接配置
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "accounting_system";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 用户注册
if(isset($_POST['signup'])){
    $username = $_POST['username'];
    $password = $_POST['password'];

    // 检查用户名是否已存在
    $sql = "SELECT * FROM users WHERE username='$username'";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) {
        echo "用户名已存在";
    } else {
        // 插入新用户信息到数据库
        $sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
        $conn->query($sql);
        echo "注册成功";
    }
}

// 用户登录
if(isset($_POST['login'])){
    $username = $_POST['username'];
    $password = $_POST['password'];

    // 验证用户名和密码是否正确
    $sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) {
        echo "登录成功";
    } else {
        echo "用户名或密码错误";
    }
}

$conn->close();
?>

<?php
// 添加记录
if(isset($_POST['add_record'])){
    $amount = $_POST['amount'];
    $date = $_POST['date'];
    $category = $_POST['category'];

    // 插入新记录到数据库
    $sql = "INSERT INTO records (amount, date, category) VALUES ('$amount', '$date', '$category')";
    $conn->query($sql);
    echo "记录添加成功";
}

<?php
// 查询记录
if(isset($_POST['search'])){
    $date = $_POST['date'];
    $category = $_POST['category'];

    // 查询符合条件的记录
    $sql = "SELECT * FROM records WHERE date='$date' AND category='$category'";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) {
        // 输出查询结果
        while($row = $result->fetch_assoc()) {
            echo "金额: " . $row["amount"]. " - 日期: " . $row["date"]. " - 类别: " . $row["category"]. "<br>";
        }
    } else {
        echo "没有找到记录";
    }
}

// 编辑记录
if(isset($_POST['edit'])){
    $record_id = $_POST['record_id'];
    $amount = $_POST['amount'];
    $date = $_POST['date'];
    $category = $_POST['category'];

    // 更新记录
    $sql = "UPDATE records SET amount='$amount', date='$date', category='$category' WHERE id='$record_id'";
    $conn->query($sql);
    echo "记录更新成功";
}

// 删除记录
if(isset($_POST['delete'])){
    $record_id = $_POST['record_id'];

    // 删除记录
    $sql = "DELETE FROM records WHERE id='$record_id'";
    $conn->query($sql);
    echo "记录删除成功";
}
?>