Oracle Interview Questions-4

31.Can null keys be entered in cluster index, normal index ?
Yes.

32.Can Check constraint be used for self referential integrity ? How ?
Yes. In the CHECK condition for a column of a table, we can reference some other column of the same table and thus enforce self referential integrity.

33.What are the min. extents allocated to a rollback extent ?
Two

34.What are the states of a rollback segment ? What is the difference between partly available and needs recovery ?
The various states of a rollback segment are :ONLINE, OFFLINE, PARTLY AVAILABLE, NEEDS RECOVERY and INVALID.

35.What is the difference between unique key and primary key ?
Unique key can be null; Primary key cannot be null.

36.An insert statement followed by a create table statement followed by rollback ? Will the rows be inserted ?
Yes.

37.Can you define multiple savepoints ?
Yes.

38.Can you Rollback to any savepoint ?
Yes.

40.What is the maximum no. of columns a table can have ?
256.