Set - 5

Question 71 :

Question What is PL/SQL ?

Answer :

PL/SQL is a procedural language that has both interactive SQL and procedural programming language constructs such as iteration, conditional branching.

Question 72 :

What are the components of OEM? (for DBA)

Answer :

Oracle Enterprise Manager (OEM) has the following components:
. Management Server (OMS): Middle tier server that handles communication with the intelligent agents. The OEM Console connects to the management server to monitor and configure the Oracle enterprise.
. Console: This is a graphical interface from where one can schedule jobs, events, and monitor the database. The console can be opened from a Windows workstation, Unix XTerm (oemapp command) or Web browser session (oem_webstage).
. Intelligent Agent (OIA): The OIA runs on the target database and takes care of the execution of jobs and events scheduled through the Console.

Question 73 :

What happens if a procedure that updates a column of table X is called in a database trigger of the same table ?

Answer :

Mutation of table occurs.

Question 74 :

Is it possible to use Transaction control Statements such a ROLLBACK or COMMIT in Database Trigger ? Why ?

Answer :

It is not possible. As triggers are defined for each table, if you use COMMIT of ROLLBACK in a trigger, it affects logical transaction processing.

Question 75 :

How many types of database triggers can be specified on a table ? What are they ?

Answer :

Insert Update Delete
Before Row o.k. o.k. o.k.
After Row o.k. o.k. o.k.
Before Statement o.k. o.k. o.k.
After Statement o.k. o.k. o.k.
If FOR EACH ROW clause is specified, then the trigger for each Row affected by the statement.
If WHEN clause is specified, the trigger fires according to the returned Boolean value.