41. Is it possible to use Transaction control Statements such a ROLLBACK or COMMIT in Database Trigger ? Why?
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.
42. What are the pl/sql statements used in cursor.
Declaring a CURSOR
Open the CURSOR
FETCH the rows from the CURSOR
CLOSE the CURSOR
43. What are the datatype used in pl/sql.
Scalar:
Single values with no internal components.
Composite:
Data items that have internal components that can be accessed individually.
Reference:
Pointers to other data items.
Large Object (LOB):
Pointers to large objects that are stored separately from other data items, such as text, graphic images, video clips, and sound waveforms.
44. What is database triggers and name some usage.
A database trigger is a named pl/sql block associated with a table and fires automatically when an event occurs or something happens. Data auditing, implementing complex business rules, security are main uses of database triggers.
45. What happens if a procedure that updates a column of table X is called in a database trigger of the same table?
Mutation of table occurs. To avoid the mutation table error, the procedure should be declared as an AUTONOMOUSTRANSACTION. By this the procedure will be treated as a separate identity.
46. What is overloading of procedure.
The Same procedure name is repeated with parameters of different datatypes and parameters in different positions, varying number of parameters is called overloading of procedures.
E.g.:
DBMS_OUTPUT .PUT_LINE
