6.6. A Table with Oracle Constraints and Business Rules
In this section a set of business rules is applied to INSERTS on the PROFESSORS table. We will initially enforce the rules with a BEFORE INSERT row trigger. This trigger will perform a variety of tasks. It will:
Override column values upon insert.
Enforce a strict business rule that may potentially result in the transaction being rejected through a call to RAISE_APPLICATION_ERROR.
Take an action. In this case print using DBMS_OUTPUT.
6.6.1. The Environment
The location of this logic is illustrated in Figure 6-2. The grayed area indicates where this trigger code fits into the overall INSERT statement process.
Figure 6-2. Location of Trigger Code.
The business rules in this example are being ...