12.5. Automatic Data Manipulation Language (DML)

Within APEX, you can write your own SQL INSERT, UPDATE, and DELETE statements or, if you build forms on tables, you can have Application Express automatically manage data manipulation for you. If you use the "Create form on a table" wizard, you will define the application metadata needed to allow Application Express to manage the INSERT, UPDATE, and DELETE of the data.

APEX uses an optimistic locking model. An optimistic locking model assumes that when an application attempts to update a row, another user has not changed it since the application queried it. If a row an application is updating is changed between the time the row is queried and the update is posted, then the update is rejected and an error message is returned to the user. If the update was instead allowed to succeed, the one user would unknowingly overwrite changes made by other users, thus creating a lost update.