Generating auto incrementing numbers with two columns - mysql

Question

I want to create a table so that I have an ID number that is based on the date, AND an ID as a unique, primary key.
Ie:
2015-2-1-1
2015-2-1-2
but, if I create:
2015-2-2-1
the counter should restart at 1.
I've tried using the following:
CREATE TABLE `invoices` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`date` date NOT NULL,
`po_id` int(11) unsigned DEFAULT NULL,
`description` varchar(256) NOT NULL,
`client_id` int(11) unsigned DEFAULT NULL,
`status` enum('unpaid','paid','partial') DEFAULT 'unpaid',
PRIMARY KEY (`id`,`date`),
UNIQUE KEY `id_UNIQUE` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=latin1;
But it doesn't work like I want.

Answer 1

If you want a two column primary key (date, id) and id that should auto increment starting from 1 each date. Just set date, for your primary column key, and id in second position in your key definition.
CREATE TABLE `invoices` (
`date` date NOT NULL,
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`po_id` int(11) unsigned DEFAULT NULL,
`description` varchar(256) NOT NULL,
`client_id` int(11) unsigned DEFAULT NULL,
`status` enum('unpaid','paid','partial') DEFAULT 'unpaid',
PRIMARY KEY (`date`, `id`)
) ENGINE=MyIsam DEFAULT CHARSET=latin1;
The internal key will be set as your example, but you will see two columns:
+----+------------+
| id | date |
+----+------------+
| 1 | 2012-01-01 |
| 2 | 2012-01-01 |
| 1 | 2012-01-02 |
| 2 | 2012-01-02 |
+----+------------+
EDIT: You have to use MyIsam format