IS420chapter16(Triggers)

How does a mutation error occur?

It occurs If the trigger body tries to directly read/update the current table

Trigger action

PL/SQL code that is executed

What is the action of the trigger?

PL/SQL code that will be automatically executed (fired) when the trigger fires

New

stores values after the modification

Old

stores values before the modification

Statement Level trigger

- Trigger fires ONCE per event (default)

Row level trigger

- Trigger fires for each row affected by the event

What happens when a trigger fires?

- all operations performed become part of the transaction of a SQL statement that caused the trigger to fire

Trigger event

- associated with the INSERT, UPDATE, or DELETE operations performed on the trigger table

Trigger timing

- before or after the event - The time when the execution of the trigger will occur

Before Timing

- implies that the trigger will be fired prior to the completion of the database event

Trigger levels

- scope affected by the trigger

Trigger

- specification of database event associated with a database table

After timing

- timing implies that the trigger will be fired after the actual database event

What statements cause triggers to fire?

-INSERT,UPDATE,DELETE

What can triggers not do?

They cannot accept input parameters, commit or rollback statements

How is a trigger executed?

They`re fired in response to database events