What you are looking for is called [Optimistic Concurrency Control](http://en.wikipedia.org/wiki/Optimistic_concurrency_control).

Add an `int` column to your table called `version`. Start at 0. 

Read a row:

    select whatever, version from mytable where id=1

Results:

    something, 0

Update a row:

    update mytable set whatever = something_new, version = 1 where id = 1 and version = 0

If that row was not found, raise an exception.

If you use an ORM like Hibernate, you can just add a field with a `@Version` annotation and it will handle this for you.