PHP로 개발된 쇼핑몰 완전할인 및 할인활동의 설계분석

CREATE TABLE `products` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(100) NOT NULL,
  `price` DECIMAL(10,2) NOT NULL,
  `stock` INT(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

CREATE TABLE `discounts` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `min_total` DECIMAL(10,2) NOT NULL,
  `discount` DECIMAL(10,2) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

ALTER TABLE `products`
ADD COLUMN `discount` DECIMAL(10,2) NOT NULL DEFAULT 0 AFTER `price`;

CREATE TABLE `activities` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(100) NOT NULL,
  `start_time` DATETIME NOT NULL,
  `end_time` DATETIME NOT NULL,
  `user_limit` INT(11) NOT NULL DEFAULT 0,
  `product_limit` VARCHAR(255) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

<?php
// 根据商品ID获取商品信息
function getProductInfo($productId) {
    // 连接数据库，查询products表
    $conn = new mysqli("localhost", "username", "password", "database_name");
    $sql = "SELECT * FROM products WHERE id = $productId";
    $result = $conn->query($sql);
    
    // 返回商品信息
    if($result->num_rows > 0) {
        return $result->fetch_assoc();
    }else {
        return false;
    }
}

// 根据满减规则计算优惠金额
function calculateDiscount($total, $discounts) {
    $discount = 0;
    
    // 根据满减规则计算优惠金额
    foreach($discounts as $d) {
        if($total >= $d['min_total']) {
            $discount = $d['discount'];
        }
    }
    
    return $discount;
}

// 根据折扣信息计算折扣价格
function calculatePrice($price, $discount) {
    return $price * $discount;
}

// 购物车结算
function checkout($productId, $quantity) {
    // 获取商品信息
    $product = getProductInfo($productId);
    
    if($product) {
        // 计算总金额
        $total = $product['price'] * $quantity;
        
        // 查询满减规则
        $conn = new mysqli("localhost", "username", "password", "database_name");
        $sql = "SELECT * FROM discounts ORDER BY min_total DESC";
        $result = $conn->query($sql);
        
        $discounts = array();
        if($result->num_rows > 0) {
            while($row = $result->fetch_assoc()) {
                $discounts[] = $row;
            }
        }
        
        // 计算优惠金额
        $discount = calculateDiscount($total, $discounts);
        
        // 根据折扣信息计算折扣价格
        $price = calculatePrice($product['price'], $product['discount']);
        
        // 最终支付金额
        $payment = $total - $discount - $price;
        
        return $payment;
    }else {
        return false;
    }
}

// 使用示例
$productId = 1;
$quantity = 2;
$payment = checkout($productId, $quantity);

if($payment) {
    echo "结算成功，应付金额：".$payment."元";
}else {
    echo "商品不存在";
}
?>