Set - 6

Question 96 :

What are snap shots and views

Answer :

Snapshots are mirror or replicas of tables. Views are built using the columns from one or more tables. The Single Table View can be updated but the view with multi table cannot be updated


Question 97 :

What are the OOPS concepts in Oracle.

Answer :

Oracle does implement the OOPS concepts. The best example is the Property Classes. We can categorize the properties by setting the visual attributes and then attach the property classes for the objects. OOPS supports the concepts of objects and classes and we can consider the property classes as classes and the items as objects


Question 98 :

What is the difference between candidate key, unique key and primary key

Answer :

Candidate keys are the columns in the table that could be the primary keys and the primary key is the key that has been selected to identify the rows. Unique key is also useful for identifying the distinct rows in the table.)


Question 99 :

What is concurrency

Answer :

Concurrency is allowing simultaneous access of same data by different users. Locks useful for accesing the database are
a) Exclusive
The exclusive lock is useful for locking the row when an insert,update or delete is being done.This lock should not be applied when we do only select from the row.
b) Share lock
We can do the table as Share_Lock as many share_locks can be put on the same resource.


Question 100 :

Previleges and Grants

Answer :

Previleges are the right to execute a particulare type of SQL statements. e.g :: Right to Connect, Right to create, Right to resource Grants are given to the objects so that the object might be accessed accordingly.The grant has to be given by the owner of the object