A way of accounting for concurrency when accessing a data-table?!

In my application multiple users can access/make records in the same data-table around the same time. The challenge here is to increment the unique id correctly which is just a simple order number [primary key]. I've solved the problem by using a Boolean flag property which changes state whenever the data-table is in use. With Boolean flag in new state, another user would have to wait a millisecond and receive a notification after a failed attempt to create a record. Would that be considered a normal practice? Thanks.