Generate Invoice & Tracking - mysql

Question

Company will receive an invoice on the 1st and 16th every month. (It will run via Cron Job every 2 week. It scan through the order table and then add into 'invoice' table. Is there alternative?)
There are list of customers orders in the orders table and it also indicate which company it belong to (orders.company_id)
The invoice table calculate the total cost of the orders from orders table.
I am trying to figure it out how to design reasonable invoices tracking. Sometime company will have to send me the fees or sometime I send them the fees (invoice.amount)
I need to track the invoices with the following:
when the company have sent me the amount
when did I sent the amount to the company
how much amount has been received from the company
how much amount did I sent to the company
did I receive the full amount (if not, what do I need to update on the Db?)
invoice status (Invoice Sent, Cancelled, Amount Received, Amount Sent)
Here is the database design I have came up with:
company table
mysql> select * from company;
+----+-----------+
| id | name |
+----+-----------+
| 1 | Company A |
| 2 | Company B |
+----+-----------+
Customers can select a company from my website.
orders table
mysql> select * from orders;
+----+---------+------------+------------+---------------------+-----------+
| id | user_id | company_id | total_cost | order_date | status_id |
+----+---------+------------+------------+---------------------+-----------+
| 1 | 5 | 2 | 25.00 | 2012-02-03 23:30:24 | 1 |
| 2 | 7 | 2 | 30.00 | 2012-02-13 18:06:12 | 1 |
+----+---------+------------+------------+---------------------+-----------+
two customers have ordered the products from Company B (orders.company_id = 2). I know the orders fields is not enough, just simplified for you.
orders_products table
mysql> select * from orders_products;
+----+----------+------------+--------------+-------+
| id | order_id | product_id | product_name | cost |
+----+----------+------------+--------------+-------+
| 1 | 1 | 34 | Chair | 10.00 |
| 2 | 1 | 25 | TV | 10.00 |
| 3 | 1 | 27 | Desk | 2.50 |
| 4 | 1 | 36 | Laptop | 2.50 |
| 5 | 2 | 75 | PHP Book | 25.00 |
| 6 | 2 | 74 | MySQL Book | 5.00 |
+----+----------+------------+--------------+-------+
List of products what customers have ordered.
invoice table
mysql> select * from invoice;
+----+------------+------------+---------------------+--------+-----------+
| id | company_id | invoice_no | invoice_date | amount | status_id |
+----+------------+------------+---------------------+--------+-----------+
| 7 | 2 | 123 | 2012-02-16 23:59:59 | 55.00 | 1 |
+----+------------+------------+---------------------+--------+-----------+
This is where I am quite stuck on invoice tables design. I am not sure how it should be done. Invoices will be generated every 2 weeks. From the result example invoice.amount is 55.00 because it has been calculated from orders.company_id = 2 table
If the invoice.amount is -50.00 (minus), it mean company will need to send me the fees amount.
If the invoice.amount is 50.00, it mean I need to send the company the fees.
The status_id could be: (1)Invoice Sent, (2)Cancelled, (3)Completed
Do I need to add invoice_id field in the orders table? Update the orders.invoice_id field when row has been inserted into 'invoice' table.
invoice_payment table
mysql> select * from invoice_payment;
+----+------------+-----------------+-------------+---------------------+---------------------+
| id | invoice_id | amount_received | amount_sent | date_received | date_sent |
+----+------------+-----------------+-------------+---------------------+---------------------+
| 1 | 1 | 0.00 | 55.00 | 0000-00-00 00:00:00 | 2012-02-18 22:20:53 |
+----+------------+-----------------+-------------+---------------------+---------------------+
This is where I can track and update transaction.. the payment will be made via BACS.
Is this good tables design or what do I need to improve? What fields and tables I should add?
If the invoice has been generated and later I need to make the changes in orders_products or orders tables - should it recalculate the invoice.amount field? (I will be using PHP / MySQL).
SQL Dump:
CREATE TABLE IF NOT EXISTS `company` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(25) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
INSERT INTO `company` (`id`, `name`) VALUES
(1, 'Company A'),
(2, 'Company B');
CREATE TABLE IF NOT EXISTS `invoice` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`company_id` int(11) NOT NULL,
`invoice_no` int(11) NOT NULL,
`invoice_date` datetime NOT NULL,
`amount` decimal(6,2) NOT NULL,
`status_id` tinyint(1) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ;
INSERT INTO `invoice` (`id`, `company_id`, `invoice_no`, `invoice_date`, `amount`, `status_id`) VALUES
(7, 2, 123, '2012-02-16 23:59:59', '55.00', 1);
CREATE TABLE IF NOT EXISTS `invoice_payment` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`invoice_id` int(11) NOT NULL,
`amount_received` decimal(6,2) NOT NULL,
`amount_sent` decimal(6,2) NOT NULL,
`date_received` datetime NOT NULL,
`date_sent` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
INSERT INTO `invoice_payment` (`id`, `invoice_id`, `amount_received`, `amount_sent`, `date_received`, `date_sent`) VALUES
(1, 1, '0.00', '55.00', '0000-00-00 00:00:00', '2012-02-18 22:20:53');
CREATE TABLE IF NOT EXISTS `orders` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`company_id` int(11) NOT NULL,
`total_cost` decimal(6,2) NOT NULL,
`order_date` datetime NOT NULL,
`status_id` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
INSERT INTO `orders` (`id`, `user_id`, `company_id`, `total_cost`, `order_date`, `status_id`) VALUES
(1, 5, 2, '25.00', '2012-02-03 23:30:24', 1),
(2, 7, 2, '30.00', '2012-02-13 18:06:12', 1);
CREATE TABLE IF NOT EXISTS `orders_products` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`order_id` int(11) NOT NULL,
`product_id` int(11) NOT NULL,
`product_name` varchar(100) NOT NULL,
`cost` decimal(6,2) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ;
INSERT INTO `orders_products` (`id`, `order_id`, `product_id`, `product_name`, `cost`) VALUES
(1, 1, 34, 'Chair', '10.00'),
(2, 1, 25, 'TV', '10.00'),
(3, 1, 27, 'Desk', '2.50'),
(4, 1, 36, 'Laptop', '2.50'),
(5, 2, 75, 'PHP Book', '25.00'),
(6, 2, 74, 'MySQL Book', '5.00');
Feel free you want to updates/add tables to Answer here.
Thanks

Answer 1

Have a look at my add-on for Gemini - SimplyFi. It will allow you to brand your invoices accordingly, can auto email them to customers when they generated, can log payments and send reminders for payments not received (statements) and has a full REST based API you can use to integrate into your system. Also may be able to benefit off the recurring billing it features.
Where you mention negative invoice amounts, those are effectively "Credit Notes" (from what I've understood from your post). Generally, you should not be changing invoices themselves after they have been issued to a client - if you need to make amendments to an amount (ie: add on, or subtract off) then you should be issuing a new invoice (for added amount), or a credit note, for subtracted amount.
Also, I would suggest you don;t send the customer money back if they are going to receive a new invoice in a few weeks time, simply keep track of their account balance, and only issue invoices or credit notes when necessary. Moving money around costs money, and you don't need to do it if it's not necessary. Just my 2 cents