Oracle Questions

%type is used to declare a field of a table while %rowtype is used to declare a record with the same type as specified in that table, view or cursor.

Example of %type:

DECLARE

         v_EmployeeName emp.ename%TYPE

Example of %rowtype

DECLARE

          v_empployee emp%ROWTYPE;

One can debug PL/SQL program by printing the output using DBMS_OUTPUT package. Put_line can be used to display a line as shown below:

BEGIN

        dbms_output.put_line(‘Sample line');

END;

- Clustering means one than one database server configured for the same user connection. When users connect, one of the server’s responds and connects based on availability. The user is completely ignorant of the fact that there are more than one database servers. It demands high cost due to infrastructure needs. Clustering is hence done on server level.

- Mirroring means, one has many configured databases on the same server. Mirrors are basically copies of the original database. Mirroring is hence done on database level. 

Named PL/SQL blocks of code which can be invoked using parameters are called PL/SQL sub programs.

Advantages of PL/SQL subprograms are

- The application makes a single call to the database to run a block of statements which improves performance against running SQL multiple times. This will reduce the number of calls between the database and the application.

- PL/SQL is secure since the code resides inside the database thus hiding internal database details from the application. The application will only make a call to the PL/SQL sub program

- PL/SQL and SQL go hand in hand so there would be no need of any translation required between PL/SQL and SQL.