Oracle Interview Questions

Oracle FAQ's

1)FOREIGN KEY constraint

A constraint that establishes a parent child relationship between two tables via one or more common columns.

The foreign key in the child table refers to a primary or unique key in the parent table.

2)Transaction

A logical unit of work consisting of one or more SQL statements that must all succeed or all fails to keep the database in a logically consistent state. A transfer of funds from one bank account is a logical

Transaction, in that both the withdrawal from one account and the deposit to another account must succeed for the transaction to succeed.

3)Schema

A named group of objects associated with a particular user account, such as tables, indexes, functions, and so forth.

4)Relational table

The most common form of a table in the Oracle database; the default type created with the

CREATE TABLE statement. A relational table is permanent and can be partitioned.

5)External table

A table whose definition is stored in the database but whose data is stored externally to the database.

6)Index

A database object designed to reduce the amount of time it takes to retrieve rows from a table. An index is created based on one or more columns in the table.

7)Composite index

If an index that is created on two or more columns in a table. This is called as Composite index.

8)Sequence

It is a database structure that automatically generates a series of numbers typically used to assign primary key values to database tables.

9)Synonyms

A synonym is an alias for another database object, such as a table, sequence, or view.

Synonyms provide easier access to database objects outside the user’s schema.

There are two kinds of synonyms: public and private. Public synonyms are Available to all database users. A private synonym is available only in the session of the schema owner who created it.

10)Username

An Oracle database account identifier that, along with a password, allows a user to connect to the database.

11)Privileges

The right to perform a specific action in the database granted by the DBA or other database users.

12)System privileges

Privileges that allow users to perform a specific action on one or more database objects or users in the database.

13)Object privileges

Privileges that allow users to manipulate the contents of database objects in other schemas.

14)ROWID

A unique identifier for a row in a table, maintained automatically in the table by the Oracle server.

ROWIDs are unique throughout the database.

15)Unique Index

In a Unique index, there are no duplicate values. An error is returned if you try to insert two rows into a table with the same index column values. By default, an index is nonunique.