Top OracleDB Interview Questions and Answers

Here are top Oracle Database interview questions,

1. What is Oracle Database?

Oracle Database is a relational database management system (RDBMS) developed by Oracle Corporation. It is widely used for managing and storing large amounts of data.

 

2. What are the main components of Oracle Database?

The main components of Oracle Database are the instance and the database. The instance consists of the memory structures and background processes, while the database contains the physical files that store the data.

 

3. What is a tablespace in Oracle Database?

A tablespace is a logical storage container in Oracle Database. It consists of one or more data files, which store the actual data.

 

4. What is the difference between a primary key and a unique key in Oracle Database?

A primary key is used to uniquely identify a record in a table and cannot contain duplicate values. On the other hand, a unique key also enforces uniqueness but allows null values.

 

5. What is the purpose of the Oracle Data Dictionary?

The Oracle Data Dictionary is a collection of database tables and views that store metadata information about the database. It provides information about the structure and properties of objects in the database.

 

6. How do you create a table in Oracle Database?

To create a table in Oracle Database, you can use the CREATE TABLE statement. For example:

CREATE TABLE table_name (

  column1 datatype,

  column2 datatype,

  ...

);

 

7. How do you insert data into a table in Oracle Database?

You can use the INSERT statement to insert data into a table. For example:

INSERT INTO table_name (column1, column2, ...)

VALUES (value1, value2, ...);

 

8. How do you update data in a table in Oracle Database?

To update data in a table, you can use the UPDATE statement. For example:

UPDATE table_name

SET column1 = value1, column2 = value2, ...

WHERE condition;

 

9. How do you delete data from a table in Oracle Database?

You can use the DELETE statement to delete data from a table. For example:

DELETE FROM table_name

WHERE condition;

 

10. What is a view in Oracle Database?

A view is a virtual table based on the result of a query. It does not store any data itself but provides a way to present data from one or more tables in a customized manner.

 

11. What is a stored procedure in Oracle Database?

A stored procedure is a named PL/SQL block that performs a specific task. It is compiled and stored in the database, and can be executed multiple times.

 

12. How do you create a stored procedure in Oracle Database?

To create a stored procedure in Oracle Database, you can use the CREATE PROCEDURE statement. For example:

CREATE PROCEDURE procedure_name

IS

BEGIN

  -- Procedure body

END;

 

13. What is a trigger in Oracle Database?

A trigger is a stored PL/SQL procedure that is automatically executed in response to a specific event, such as an insert, update, or delete operation on a table.

 

14. What is a cursor in Oracle Database?

A cursor is a temporary work area in Oracle Database that allows you to retrieve and manipulate data from the result set of a query.

 

15. How do you create a cursor in Oracle Database?

To create a cursor in Oracle Database, you can use the DECLARE CURSOR statement. For example:

DECLARE

  cursor_name CURSOR FOR SELECT column1, column2 FROM table_name;

 

16. What is normalization in Oracle Database?

Normalization is the process of organizing data in a database to eliminate redundancy and improve data integrity. It involves breaking down tables into smaller, more manageable parts.

 

17. What is the difference between a commit and a rollback in Oracle Database?

A commit is a statement that makes permanent changes to the database, saving the current transaction. A rollback, on the other hand, cancels all the changes made within the current transaction and restores the database to its previous state.

 

18. What is the purpose of an index in Oracle Database?

An index is a database object that improves the speed of data retrieval by providing fast access to specific rows in a table. It is created on one or more columns of a table.

 

19. What is the role of the Oracle optimizer?

The Oracle optimizer is responsible for determining the most efficient way to execute a SQL statement. It analyzes various execution plans and selects the one with the lowest cost.

 

20. How do you monitor performance in Oracle Database?

Oracle provides several tools for performance monitoring, such as Enterprise Manager, Automatic Workload Repository (AWR), and Automatic Database Diagnostic Monitor (ADDM). These tools help identify performance bottlenecks and suggest tuning recommendations.

Above are few top Oracle Database interview questions. Remember to prepare and expand on these answers.

Good luck with your interview!  👍