SQL View — A Complete Guide

In today’s world, data is being created at very high rates, and it is a big challenge to deal with these massive amounts of data.When a data scientist deals with data, many filters and tweaks in data are needed to be done to reach correct conclusions.The freedom to view data in small pieces that satisfy the provided conditional without wasting extra memory proves to be a boon.

SQL views help us to assess and understand data, while the efficiency of a system is taken care of by the virtual property of the view.

INTRODUCTION :

SQL is a popular database query language.

It has applications in various use cases of software designing.

When we query the available data, we also come across data that is not required by us or is of little or no use.

SQL views come in hand here. By using SQL views, we can easily modify and access the data we need.

The view creates a virtual table on which we can execute all types of queries and transaction statements.

Views in SQL are kind of virtual tables. A view also has rows and columns as they are in a real table in the database. We can create a view by selecting fields from one or more tables present in the database. A View can either have all the rows of a table or specific rows based on certain condition.

https://www.codeproject.com/KB/database/View/View1.JPG

What are SQL Views?

• SQL views are virtual tables created by using a CREATE VIEW statement.
• Views do not take up extra memory and are not stored but can be used by their names and can be further queried using SQL statements.
• By using SQL views, we can create a virtual table consisting of the columns we require.
• We can even use conditionals and WHERE clause while creating the view to get the data that follows a certain specified constraint.

The basic syntax of CREATE view is as follows

Syntax:

CREATE VIEW view_name AS

SELECT column1, column2, …

FROM table_name

WHERE condition;

Types of SQL views

In SQL, there are several types of views that can be created based on their characteristics and functionality. The common types of SQL views include:

1. Simple views: Simple views are the most basic type of view. They are derived from a single table and contain a subset of the columns or rows from that table. Simple views do not involve any complex calculations or joins.
2. Complex views: Complex views are created from multiple tables and involve joins, calculations, or aggregations. They can combine data from different tables to present a comprehensive view of the data. Complex views are useful when you need to retrieve information that spans multiple tables.
3. Updatable views: Updatable views allow modifications (insert, update, delete) to be performed on the view, which in turn updates the underlying tables. The updates are propagated to the base tables through the view. However, not all views are updatable, as certain conditions and restrictions need to be met, such as having a single base table or meeting specific criteria in terms of column constraints.

These are some of the commonly used types of SQL views. The choice of the view type depends on the specific requirements and goals of your database and application.

Comparison between simple and complex SQL views :

https://images.app.goo.gl/jhJfWs1xrsgPa5B67

Advantages of SQL views

SQL views are useful for several reasons:

1. Data abstraction: Views provide a layer of abstraction over the underlying tables in a database. They allow you to create a virtual representation of the data that can be used by applications or other database users without revealing the complexity or structure of the underlying tables. Views can present a simplified, customized, or aggregated view of the data, hiding unnecessary details and making it easier to work with.
2. Simplify complex queries: Views can simplify complex SQL queries by encapsulating them into a single, reusable object. Instead of writing and maintaining a complex query multiple times, you can create a view that encapsulates the logic and use it whenever needed. This improves code readability, maintainability, and reduces the chances of errors.
3. Security and access control: Views can be used to enforce security and access control in a database. You can create views that restrict the columns or rows visible to certain users or user groups. For example, you can create a view that only exposes specific columns of a table to certain users, hiding sensitive information. This helps protect the integrity and confidentiality of the data.
4. Data consistency and integrity: Views can help maintain data consistency and integrity by enforcing business rules or data transformations. You can create views that combine data from multiple tables and apply validation or transformation rules to ensure that the data conforms to certain requirements. This helps to prevent data inconsistencies and ensures the accuracy of the data presented through the views.

Overall, SQL views provide a flexible and powerful mechanism for managing data, simplifying queries, enforcing security, optimizing performance, and maintaining data consistency in a database environment.

View creation in MYSQL :

In order to create a view we need to have at least two tables in our database. Here we are selecting two tables from our database named as customer and vehicles. here we have choosen tables which we have already created in our database.

Basic syntax to create table are :

vehicles table creation : create table vehicles(ID int,colour varchar(100),owner varchar(100),brand varchar(100),type varchar(100));

customer table creation : create table customer(owner varchar(100),number int,customerID int)

Simple view creation :

In SQL, a simple view is a virtual table that consists of a SELECT statement. It is a named query that retrieves data from one or more tables and presents it as a single table
Creating a simple view involves specifying the columns to be included,the tables to be used, and the WHERE clause to filter data.
The view can then be queried like any other table, but its data is actually derived from the underlying tables.
syntax:

CREATE VIEW view_name AS

SELECT column1, column2, …

FROM table_name

WHERE condition;

Multiple table view creation :

In SQL, you can create multiple views in a database. Each view can be defined using its own SELECT statement, specifying which columns and tables should be included in the view. To create multiple views in SQL, you can use the CREATE VIEW statement multiple times, each time providing a unique name for the view and its associated SELECT statement.

syntax

CREATE VIEW view name AS select table1.column1,table2.column2 from table1,table2 WHERE condition ;

Applications of SQL views :

SQL views have numerous real-life applications across various industries. Here are a few examples:

1. Customer Relationship Management (CRM): In CRM systems, SQL views can be used to consolidate customer data from multiple tables or databases into a single, unified view. This allows customer service representatives to access comprehensive information about customers, such as contact details, purchase history, and interactions, in real-time.
2. E-commerce and Online Retail: SQL views can be employed in e-commerce platforms to create personalized product recommendations for customers. Views can combine customer data, purchase history, and product information to generate real-time recommendations based on user preferences and behavior.
3. Healthcare Management: In healthcare systems, SQL views can provide a unified view of patient records, combining data from different sources like electronic health records, lab results, and medical imaging. This allows healthcare professionals to access up-to-date patient information in real-time, enabling accurate diagnoses and efficient treatment.
4. Financial Analysis: SQL views are valuable in financial institutions for real-time financial analysis and reporting. Views can consolidate data from various financial systems and provide a holistic view of financial performance, cash flows, and key metrics. This facilitates timely decision-making and risk management.

These real-life applications highlight the usefulness of SQL views in managing and analyzing data in diverse industries, improving operational efficiency, and supporting informed decision-making. The flexibility and customizable nature of views make them a valuable tool for creating tailored views of data to meet specific business needs.

CONCLUSION

In conclusion, SQL views are powerful and versatile tools in database management. They provide a layer of abstraction, simplifying data access and allowing users to work with customized and focused views of the data. Views offer advantages such as improved data security, simplified query construction, enhanced performance, and data consistency. They find real-life applications in various domains, including reporting, analytics, data integration, application development, and compliance. SQL views facilitate efficient data management, analysis, and decision-making, making them an essential component in modern database systems.

REFERENCES

1. https://www.w3schools.com/sql/sql_view.asp
2. https://www.tutorialspoint.com/sql/sql-using-views.htm
3. https://www.javatpoint.com/dbms-sql-view
4. https://www.simplilearn.com/tutorials/sql-tutorial/view-in-sql
5. https://learnsql.com/blog/sql-view/

Authors :

1. Lalit Chaudhari
2. Akanksha Jadhav
3. Akshada Kakade
4. Vaibhavi Kakade
5. Utkarsh Kandare
6. Hemal Kulkarni