Chapter 16. Triggers
A trigger is a special PL/SQL procedure that fires, or executes, in response to a specific triggering event. For example, you might write a trigger to enforce a business rule on INSERT statements on a particular table, maintain referential integrity in a distributed database, or track user logons. A trigger has three parts:
A header line that defines the triggering event
An optional WHEN clause that restricts the trigger’s firing to a specific condition (for example, the trigger fires only when salary is greater than $50,000)
The actual trigger code itself
This chapter tests your ability to define triggers for a variety of events, work with correlation variables (special pseudo-column names that represent things like the old and new values of a column), and use triggers to implement business logic.
Beginner
16-1. | What is a trigger? |
16-2. | For which of the following events can you create a trigger?
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16-3. | What is one of the main differences between the execution of a trigger and the execution of a stored procedure? |
16-4. | What are the two modes a trigger can have? |
16-5. | Which of the following terms describes the situation in which the execution of one trigger results in the execution of another, or possibly more, different triggers?
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