构建生产计划排程功能的企业资源计划（ERP）系统的PHP开发

// 创建数据库连接
$conn = mysqli_connect('localhost', 'root', '', 'production_schedule');

// 创建"products"表格
$sql = "CREATE TABLE products (
    id INT(11) PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(100) NOT NULL,
    quantity INT(11) NOT NULL
)";
mysqli_query($conn, $sql);

// 创建"production_orders"表格
$sql = "CREATE TABLE production_orders (
    id INT(11) PRIMARY KEY AUTO_INCREMENT,
    product_id INT(11) NOT NULL,
    quantity INT(11) NOT NULL,
    due_date DATE NOT NULL,
    CONSTRAINT FK_product_id FOREIGN KEY (product_id) REFERENCES products (id)
)";
mysqli_query($conn, $sql);

// 查询所有产品
$sql = "SELECT * FROM products";
$result = mysqli_query($conn, $sql);

// 循环处理每个产品
while ($row = mysqli_fetch_assoc($result)) {
    $product_id = $row['id'];

    // 查询该产品的所有生产订单，并按照截止日期从小到大排序
    $sql = "SELECT * FROM production_orders WHERE product_id = $product_id ORDER BY due_date ASC";
    $orders_result = mysqli_query($conn, $sql);

    // 计算起始日期为当前日期
    $start_date = date('Y-m-d');

    // 循环处理每个生产订单
    while ($order_row = mysqli_fetch_assoc($orders_result)) {
        $quantity = $order_row['quantity'];
        $due_date = $order_row['due_date'];

        // 计算该生产订单需要的天数
        $days = ceil($quantity / $row['quantity']);

        // 根据起始日期和需要的天数计算出结束日期，并更新下一个订单的起始日期
        $end_date = date('Y-m-d', strtotime($start_date . " + $days days"));
        $start_date = $end_date;

        // 更新生产订单的开始日期和结束日期
        $order_id = $order_row['id'];
        $sql = "UPDATE production_orders SET start_date = '$start_date', end_date = '$end_date' WHERE id = $order_id";
        mysqli_query($conn, $sql);
    }
}