Introduction:
In the world of databases, managing and accessing complex data efficiently is essential. SQL Views offer a smart and powerful way to simplify this process. SQL (Structured query language), which is the programming language for the selection, insertion, and updating of data into different database structures, is taught in all database-related courses.
A notable feature that is possible when writing SQL commands is employing an SQL View, which can minimize query complexity, enhance security, and keep the code neat and tapered. If you are a beginner still working your way through SQL, knowledge of SQL Views will be beneficial for you.
In this article, we will take you through SQL Views, their creation, application, and impacts on real-life database projects.
What is a View in SQL?
An SQL View is a virtual table. It does not store data physically like a real table but presents data from one or more tables in a customized way. You can think of a view as a saved SQL query that you can use, just like a table.
By way of instance, if you frequently need to run complex SQL queries to extract information from multiple tables, you can save that particular query as a View and simply treat it like any other table when you need it.
Why to Use SQL Views?
SQL Views provide several powerful benefits that make them a valuable tool in any database system. There are different reasons to create SQL Views.
1) Simplify Complex Queries:
Views provide an easier route to the readability and manageability of your query. Instead of repeatedly writing lengthy SELECT queries, you can just mention the short name of the view.
2) Enhance Security:
You can limit access to sensitive data by allowing users to access only certain columns or rows through a view without giving full access to the actual tables.
3) Data Consistency:
Every time the Views are called or accessed, they are guaranteed to return the same result unless there are changes to the underlying tables.
4) Reusability:
It allows you to reuse complex queries without writing them once again. If you are writing a query, you don't need to repeat it. The main aim of the reusability is to make your code cleaner and easier to maintain.
5) Maintainability:
If the logic in your queries changes, you only need to update the view, not every query in your application.
How to Create a View in SQL?
In SQL, we can easily create a view using the CREATE VIEW statement.
Syntax:
CREATE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;
Example:
CREATE VIEW SalesEmployees AS
SELECT employee_id, name, department
FROM Employees
WHERE department = 'Sales';
Explanation:
In the above query, you create a view that show only the details of the employee table who work in the Sales department.
Now, instead of writing the full query every time, you can simply do the following:
SELECT * FROM SalesEmployees.
Using a View:
Once created, a view can be used in SELECT queries just like any regular table.
Examples:
To fetch all records:
SELECT * FROM SalesEmployees;
To filter further records:
SELECT name FROM SalesEmployees WHERE employee_id > 100;
To join with another table:
SELECT s.name, d.location
FROM SalesEmployees s
JOIN Departments d ON s.department = d.name;
Updating Data Through a View:
This may go ahead only if certain conditions pertaining to the view are met as follows:
The view is related to a single table.
The view shall not have any applications of GROUP BY or DISTINCT or in functions such as SUM or AVG.
Example:
UPDATE SalesEmployees
SET department = 'Marketing'
WHERE employee_id = 102.
This works only if the database has allowed it and if the view is updatable.
How-to Update a View?
Whenever you need to update the definition of some view, the CREATE above OR REPLACE statement can be used.
Example:
CREATE OR REPLACE VIEW SalesEmployees AS
SELECT employee_id, name, department, salary
FROM Employees
WHERE department = 'Sales';
This view would now include the salary column as well.
How to Delete a View?
Any view that is no longer required can be deleted using the following command: DROP VIEW.
Example:
DROP VIEW SalesEmployees;
This command will delete the view from the database but not the underlying data from the tables.
Types of Views in SQL
SQL Views can be divided mainly into two types.
1.Simple View:
• Based on a single table
• Doesn't use functions or joins
• Usually allows updates
2. Complex View:
• Based on multiple tables
• Uses joins, functions, or groupings
• Usually read-only
• Advantages of Using Views
• Reduces code duplication
• Protects sensitive data
• Makes querying easier
• Improves application security
• It can be used to generate reports quickly
Disadvantages of Using Views
• Sluggish Performance: If the view happens to be complex, slower query execution is expected.
• Not all updates allowed: Some views are simply read-only.
• Performance Issues: This is the main drawbacks of using views to reduce the performance.
Best Practices for Using Views:
• Meaningful naming conventions should be used with respect to the view.
• Avoid unnecessary complexity in views.
• A periodic audit of views to assess usefulness and efficiency.
• Limiting data exposure by developing views giving access to required data only.
Conclusion
In the article, SQL Views: What They Are and How to Use Them, SQL Views are very important feature which facilitates an easier and more secure way of working with databases. Regardless of whether large applications are being developed or one is just attempting to grasp SQL, views would save time, lessen code repetition, and protect sensitive data. They are virtual tables that show data according to your defined query without storing any additional data.
I suggest you learn the SQL Programming language from the Tpoint tech website as this website provides SQL tutorials, interview questions, and an Online SQL Compiler as well.