Oracle Interview Questions and Answers on SQL Queries and Database Theory

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Frequently asked basic and advanced Oracle Database Interview Questions and Answers on Database theory and SQL Queries with Examples for Freshers and Experienced DBA, Java, PHP, .Net Developers.

1. What is oracle database ?

Oracle Database is a relational database management system (RDBMS) which is used to store and retrieve the large amounts of data. Oracle Database had physical and logical structures. Logical structures and physical structures are separated from each other

2. Explain oracle grid architecture?
Grid computing is a information technology architecture that provides lower cost enterprise information systems. Using grid computing, independent hardware, and software components can be connected and rejoined on demand to meet the changing needs of businesses. It also enables the use of smaller individual hardware components.
3. What is the difference between large dedicated server and oracle grid?
Large dedicated server:
  • It has expensive costly components.
  • High incremental costs.
  • It has single point of failure.
  • Enterprise service at higher cost.
Oracle Grid:
  • It has low cost modular components.
  • Low incremental costs.
  • It has no single point of failure.
  • Enterprise service at low cost.


4. What are the computing components of oracle grid?

The computing componenets of oracle grid are:

  • Oracle Enterprise Manager and Grid Control
  • Oracle 10g Database and Real Application Clusters.
  • ASM Storage Grid.

5. What is server virtualization?

Oracle Real Application Clusters 10g (RAC) enables a single database to run across multiple clustered nodes in a grid, pooling the processing resources of several standard machines.

6. What is storage virtualization?

The Oracle Automatic Storage Management (ASM) is a feature of Oracle Database 10g which provides a virtual layer between the database and storage so that group of disks can be treated as a single disk group and disks can be dynamically added or removed while keeping databases online.

Also Read Basic to Advanced Oracle SQL Query Interview Question and Answers

7. What is Grid Management feature?

The Grid Management feature of Oracle Enterprise Manager 10g provides a single console to manage multiple systems together as a logical group.

8. When oracle allocates an SGA?

When Oracle starts, it reads the initialization parameter file to determine the values of initialization parameters. After this, it allocates an SGA and creates background processes.

9. What is an oracle instance?

When you start, the database instance comes into picture into system memory. Combination of the SGA and the Oracle processes is called an Oracle instance.

10. What are the several tools for interacting with the oracle database using sql?

There are several tools for interfacing with the database using SQL:

  • Oracle SQL*Plus and iSQL*Plus 
  • Oracle Forms, Reports, and Discoverer
  • Oracle Enterprise Manager 
  • Third-party tools

11. How oracle works?

  • An instance has started on the database server.
  • A client established a connection to the server, using the proper Oracle Net Services driver.
  • The server creates a dedicated server process on behalf of the user process.
  • The user executes SQL statement and commits the transaction.
  • The server process receives the statement and checks for any shared SQL area that contains a similar SQL.
  • The server process retrieves data from datafile (table) or SGA.
  • The server process modifies data in the SGA area. The DBWn process writes modified blocks permanently to disk. The LGWR process records the transaction in the redo log file.
  • The server process sends a message to the application.
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