Multi-user environment

Running the application in a multi-user environment requires us to take special precautions to ensure our data integrity and consistency. Most novice developers, and also many of the experienced ones, aren't always aware of issues like concurrency control, lost updates, and locking mechanisms. Even if you are aware of these potential problems, you may not always know what to do about them.

In the Web environment we are usually using a locking mechanism called optimistic lock (which we reviewed in chapter 14). All the APEX built-in DML processes are implemented using this locking method. However, as we reviewed in Chapter 9, about APEX Processes, these built-in processes are not always suited to our needs and demands so we need to code our own DML processes.

I want to remind you that the option of using the Object Browser to create PL/SQL packages includes all the necessary functionalities to perform all the necessary DML operations on specific database tables of...