Introduction:

In the realm of Oracle SQL, views serve as powerful tools for simplifying complex queries, enhancing data security, and improving overall database management. Understanding how to leverage views effectively can significantly streamline your workflow and optimize database performance. In this comprehensive guide, we will delve into the intricacies of Oracle SQL views, exploring their functionalities, benefits, and best practices for implementation.

What is an Oracle SQL View?

At its core, an Oracle SQL view is a virtual table derived from one or more tables or other views. Unlike physical tables, views do not store data themselves; instead, they present data from underlying tables in a structured format. Views essentially act as stored queries, allowing users to encapsulate complex logic, perform data abstraction, and create simplified interfaces for data retrieval.

Benefits of Oracle SQL Views:

Simplified Data Access: Views enable users to encapsulate complex SQL queries into easily accessible structures, simplifying data retrieval for end-users.
Data Abstraction: Views provide a layer of abstraction, allowing users to interact with summarized or filtered data without exposing the underlying table structure.
Enhanced Security: Views can restrict access to specific columns or rows, ensuring that sensitive information remains protected while still providing necessary data access. 
Performance Optimization: By predefining frequently used queries as views, Oracle SQL can optimize query execution plans, improving overall performance and scalability.

Here’s a breakdown of creating, deleting, and updating views in Oracle SQL:

1. Creating a View:

The CREATE VIEW statement defines a view. It requires two main parts:

• View Name: This is the name you assign to the view, similar to a table name.
• SELECT statement: This defines the data retrieved and formatted for the view.

CREATE VIEW view_name AS
SELECT column1, column2, ...
FROM base_table
WHERE condition;

view_name: Assigns a unique name to your view for future reference.
column1, column2, …: (Optional) Explicitly defines the names of columns in the view.
SELECT: Initiates the selection of data from the base table(s).
FROM base_table: Specifies the base table(s) from which data is retrieved.
WHERE condition (Optional): Filters the data based on a specific criterion.

2. Deleting a View:

The DROP VIEW statement removes a view from the database.

DROP VIEW view_name;

3. Updation

In Oracle SQL, you cannot directly perform an UPDATE on a view in most cases. However, you can achieve similar functionality by updating the underlying tables of the view.

Here’s a general approach:

1. Identify the base tables that the view is built upon.
2. Perform UPDATE statements on those base tables.
3. Refresh the view if necessary.

For example, if you have a view named my_view which is based on tables table1 and table2, you would update those tables directly:

UPDATE table1
SET column1 = 'new_value'
WHERE <condition>;

UPDATE table2
SET column2 = 'new_value'
WHERE <condition>;

After updating the base tables, you might need to refresh the view to reflect the changes:

COMMIT;

ALTER VIEW my_view 
COMPILE;

You can also create triggers called INSTEAD OF triggers that intercept modification statements targeting the view and translate them into equivalent operations on the underlying tables.

Best Practices for Oracle SQL Views:

Avoid creating overly complex views that may hinder performance or maintainability.
Optimize View Definitions: opt for efficient query structures within views to ensure optimal performance.
Document Views Thoroughly: Provide comprehensive documentation for views, including their purpose, dependencies, and usage guidelines.
Regularly Review and Refactor Views: Periodically review existing views to identify opportunities for optimization or consolidation.

Here are some practical scenarios where views can be Implemented:

Presenting a Simplified View of Customer Data: Create a view that displays only essential customer information like name, contact details, and purchase history, masking sensitive data like credit card numbers.
Calculating Sales Commission: Develop a view that computes commission based on specific sales criteria, simplifying calculations for sales representatives.
Monitoring Database Activity: Design a view to track user login attempts and database modifications, aiding in security audits.
By leveraging views effectively, you can streamline data access, bolster data security, and simplify data management within your Oracle database environment.

Conclusion:
Oracle SQL views are indispensable tools for database management, offering a myriad of benefits ranging from simplified data access to enhanced security and performance optimization. By mastering the art of creating and utilizing views effectively, database professionals can streamline their workflows, improve data accessibility, and elevate overall database performance. Embrace the power of Oracle SQL views to unlock new possibilities in data management and analysis.