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What is a view in SQL databases?

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If you are a database developer or preparing for an SQL interview, you might encounter the question: what is a view in SQL databases? A view is a virtual table that contains data from one or more base tables or views. It does not store any data itself, but rather displays the result of a predefined query. In this article, you will learn why views are useful, how to create and use them, and what are some of the advantages and disadvantages of views.

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Harshita Girdhar

??Passionate AI & ML Learner | Python Lover ??| Robotics Enthusiast | Ex- Intern at NIELIT | Merging My Passion for…
Taleya Husn

Associate Data Engineer at Khushi Baby
Claudio S.

Delivery Manager | Customer Success | Operational Excellence | Fleet Management Systems | Continuous Improvement

1 Why use views?

Views can simplify complex queries by hiding the details of the underlying tables or views. For example, you can create a view that joins several tables and filters some columns, and then use the view name instead of writing the whole query every time. Views can also provide a consistent and logical way of accessing data, regardless of how the data is physically stored or organized. For example, you can create a view that shows the latest sales data, even if the base tables are updated frequently. Views can also enhance security and privacy by restricting access to certain columns or rows of data. For example, you can create a view that only shows the name and salary of employees, and grant access to the view instead of the base table that contains more sensitive information.

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Harshita Girdhar

??Passionate AI & ML Learner | Python Lover ??| Robotics Enthusiast | Ex- Intern at NIELIT | Merging My Passion for Innovation and Problem-solving to Drive Breakthroughs in the Robotics Industry????
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Views allow to encapsulate complex SQL queries into a virtual table-like structure.Like instead of writing lengthy and complicated queries repeatedly again and again you can simply write a view with the query, simplifying subsequent access to that data.

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Taleya Husn

Associate Data Engineer at Khushi Baby
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Views in SQL offer several advantages, making them a valuable tool in database management. They allow for the simplification of complex queries by abstracting underlying table details. This simplification enhances code readability and facilitates maintenance. Views also provide a consistent and logical means of accessing data, irrespective of how it's physically stored or organized, promoting a standardized approach to data retrieval. Additionally, views promote code reusability by encapsulating complex logic. They act as virtual tables, allowing users to reference them instead of repeatedly writing intricate queries. This not only streamlines development but also reduces the risk of errors.

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Claudio S.

Delivery Manager | Customer Success | Operational Excellence | Fleet Management Systems | Continuous Improvement
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Las vistas permiten simplificar consultas complejas. Puedes crear una vista que encapsule una consulta complicada y luego usar esa vista en otras consultas como si fuera una tabla regular. Esto hace que el código sea más legible y fácil de mantener y que en general la reportabilidad que generes sea mas limpia al apuntar directamente a una vista que tenga solo las columnas que efectivamente necesitas consultar.

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Rishabh Gangal
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Views in SQL are direct windows into your data. They're calculated tables, enhancing security by showing only what's necessary, keeping things safe and tidy. Easy to create with CREATE VIEW, and using them is same as working with regular tables —select, insert, update, delete. Views keep things organized and offer a clean perspective, but tend to become complex to maintain.

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HongBin Ding
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A view is a virtual table generated from the result set of a SQL query. It does not store any data on its own but is a saved SQL query that can be used as a table for querying purposes. Views allow users to simplify complex queries by encapsulating frequently used logic or joins into a reusable object. They present a way to customize and present subsets of data to different users without altering the original tables, enhancing security by restricting access to specific columns or rows and providing a layer of abstraction over the underlying database schema.

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2 How to create views?

To create a view, you need to use the CREATE VIEW statement, followed by the name of the view and the query that defines the view. For example, the following statement creates a view called emp_view that shows the name, department, and salary of employees from the emp table:

CREATE VIEW emp_view AS
SELECT name, dept, salary
FROM emp;

You can also specify some options for the view, such as whether it is temporary, updatable, or checkable. For example, the following statement creates a temporary view that is deleted when the session ends:

CREATE TEMPORARY VIEW temp_view AS
SELECT * FROM emp_view;

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Phillip Morphis

Database Developer / Database Analyst / Database Specialist
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You create a view by using the "CREATE VIEW" statement. An example would be: CREATE VIEW topFiveEmps AS select emplid, employeeFirstName, employeeLastName, positionNbr, reportsTo from employees order by employeeLastName, employeeFirstName fetch first 5 rows only This will create a pretty useless view that'll return 5 employees. If you're using SQL Server, just change the guts to "select top 5" ... and remove the "fetch first 100 rows only"

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3 How to use views?

You can use views in the same way as you use base tables in SQL queries. For example, you can select, insert, update, or delete data from a view, as long as the view is updatable and does not violate any constraints. You can also join, group, or filter data from a view, or use a view as a subquery or a derived table. For example, the following query uses the emp_view as a subquery to find the average salary of each department:

SELECT dept, AVG(salary) AS avg_salary
FROM (SELECT * FROM emp_view) AS sub
GROUP BY dept;

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4 Advantages of views

Views can offer several advantages for database development and management, such as simplifying complex queries and making them easier to read and maintain. Additionally, views can provide a consistent and logical view of data, regardless of its physical organization. Moreover, views can enhance security and privacy by limiting access to certain columns or rows of data. Furthermore, views can improve performance by caching the results of the query that defines the view. Finally, views can facilitate data abstraction and modularity by concealing the details of the data source.

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Rahul Pradhan

Full-Stack Developer | Ex- Full-stack developer @Piplub | Cloud & DevOps | AI & GenAI Enthusiast | AWS | 2xOracle Certified | Postman student expert | Salesforce 50+ badges
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Views are the virtual tables they are used to create views to rename columns for business purposes, If the column name doesn't line up the terminology of the business wants to use. And more it also provides security that can be used to limit visibility of data, and also the main advantage is the Reusability in which we can easily access our SQL queries without having to re-write SELECT statement multiple times...

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5 Disadvantages of views

When working with views, it's important to be aware of some drawbacks. For instance, views can introduce overhead and complexity if the query defining the view is complex or involves multiple joins or aggregations. Additionally, views can lead to data inconsistency or errors if the base tables or views are modified or dropped without updating or dropping the view accordingly. Furthermore, certain SQL operations, such as indexes, triggers, or constraints, may be limited in functionality and flexibility depending on the type and options of the view. Finally, views can affect the accuracy and timeliness of data depending on how often the view is refreshed or synchronized with the base tables or views.

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Rahul Pradhan

Full-Stack Developer | Ex- Full-stack developer @Piplub | Cloud & DevOps | AI & GenAI Enthusiast | AWS | 2xOracle Certified | Postman student expert | Salesforce 50+ badges
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As every thing has a drawback looking at the views, The main problem mostly used to face is it's difficult to maintain especially when they are used in complex quires . One more common issue is it leads to reduce the performance of SQL queries it's basically slow down when dealing with the large and complex datasets.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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What is a view in SQL databases?

1

2

3

4

5

6

1 Why use views?

2 How to create views?

3 How to use views?

4 Advantages of views

5 Disadvantages of views

6 Here’s what else to consider

Database Development

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What is a view in SQL databases?

1

2

3

4

5

6

1 Why use views?

2 How to create views?

3 How to use views?

4 Advantages of views

5 Disadvantages of views

6 Here’s what else to consider

Database Development

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