TOP 20 INTERVIEW QUESTION AND ANSWERS FOR ORACLE DATABASE ADMINISTRATOR

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

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

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

• Tables
• Views
• Synonyms
• Table space
• Indexes
• Sequences

The objects as such can be placed in the database. The language of the DBMS can be equated with an object-oriented programming language. The communication 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.

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

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

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

The NULL value in oracle shows missing data or unknown. 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.

Varchar                          
It stores up to 2000 bytes   
It occupies space for NULL value  
varchar2
It can store up to 4000 bytes
 It will not hold any space

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

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

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

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

Hash Cluster is a system used to store the table to make it quicker to recover. To recover the rows from the table, implement the hash value on the table.

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

SET operators are applied to two or more queries. The operators are Union All-Union, intersect and Minus.

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

The Oracle grid architecture has the wide range of servers, storage, and networks into a flexible, on-demand processing resource for enterprise computing needs. The grid computing infrastructure continually analyzes the demand for resources and adjusts supply accordingly.
Grid computing applies classy workload management that makes it probable for submissions to share resources across many servers. Data processing function 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.