Top Interview Question and Answers for Oracle Database Administrator

  1. What is Oracle?

Oracle is a database server, which manages data in in an extremely organized manner. It enables users to store and recover relevant data in a multiuser environment so that many users can simultaneously access the same data. In addition to this, a database server checks unapproved access and delivers effective solutions for failure recovery.

  1. Define Oracle Database?

An Oracle database is a group of data treated as a unit. It is used to store and recover related information. A database server plays a key role in solving the problems of information management. It includes physical and logical structures in which system, user and control data is stored. The software that manages the database is called the Oracle database server.

  1. Explain the roles of DBA?

DBA creates new users, eliminate existing users or modify any of the environment variables or privileges assigned to other users.

  • Manage storage for database
  • Regulate clients and security
  • Manage outline objects
  • Monitor and manage database performance
  • Perform backup and recovery
  • Plan and automate jobs


  1. What are different types of Oracle database objects?
  • Tables
  • Views
  • Indexes
  • Synonyms
  • Sequences
  • Tablespace
  1. What are the advantages of ORDBMS?

The objects as such can be placed in the database. The language of the DBMS can be coordinated with an object- oriented programming language. The language may even be accurately the same as that used in the application, which does not compel the developer to have two representations of his objects.


  1. What is an Oracle index?

An oracle index is a flexible structure connected with a table to get a direct access to rows, which can be created to boost the performance of data recovery. Index can be created on one or more columns of a table.

  1. What is the use of RAW Datatype?

RAW data type is used in storing values in binary data format. The maximum size of a RAW in a table is 32767 bytes.

  1. What is BLOB datatype?

A BLOB data type is a binary string with a changing length. It is used to store two gigabytes memory. Length for BLOB is stated in Bytes.

  1. What is NULL value in Oracle?

NULL value in oracle shows unknown or missing data. It is used as a default entry demonstrating that no actual data is present.


The WITH CHECK option clause states the level of check to be done in DML statements. It aids in preventing variations to a view that would produce results not contained in the sub query.

  1. What is the difference between varchar and varchar2 data types?


It store up to 2000 bytes It can store up to 4000 bytes
It occupy space for NULL value It will not occupy any space
  1. What is the use of NVL function?

The NVL function is used to replace NULL values with another value. e.g.  NVL (Value, replace value)

  1. How do we get field detail of a table?

To know the field detail of a table, Describe <Table_Name>

  1. What is an ALERT?

An alert is a window which shows up in the center of the screen and overlays a part of the current play.

  1. What is the fastest query method to fetch data from the table?

ROW ID is the fastest query method for fetching data from the table.

  1. What is the parameter mode that can be passed to a procedure?

The parameter modes that can be passed to a procedure are IN, OUT and INOUT

  1. What is hash cluster?

Hash Cluster is a technique used to store the table to make it quicker to recover. In order to retrieve the rows from the table, implement the hash value on the table.

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  1. What are SET operators?

SET operators are used with two or more queries. The operators are Union, Union All, intersect and Minus.

  1. What is a view?

View is a logical table that depends on one or more tables and views. The tables on which the view is based upon are called Base Tables and it contains no data.

  1. Explain Oracle Grid Architecture?

The Oracle grid architecture has wide range of servers, storage, and networks into a flexible, on-demand processing resource for enterprise computing needs. The grid computing infrastructure constantly analyzes demand for resources and adjusts supply accordingly.

Grid computing uses classy workload management that makes it possible for submissions to share resources across many servers. Data processing capacity can be added or eliminated on demand, and resources within a location can be vigorously provisioned. Web services can rapidly integrate applications to create new business processes


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