Defining Composite Key with Auto Increment in MySQL

Question

Scenario:

I have a table which references two foreign keys, and for each unique combination of these foreign keys, has its own auto_increment column

Answer 1

You can use a unique composite key for sr_no,app_id & test_id. You cannot use incremental in sr_no as this is not unique.

CREATE TABLE IF NOT EXISTS `issue_log` (
  `sr_no` int(11) NOT NULL,
  `app_id` int(11) NOT NULL,
  `test_id` int(11) NOT NULL,
  `issue_name` varchar(255) NOT NULL,
  UNIQUE KEY `app_id` (`app_id`,`test_id`,`sr_no`)
) ENGINE=InnoDB ;

I have commented out unique constraint violation in sql fiddle to demonstrate (remove # in line 22 of schema and rebuild schema )