SQL CREATE VIEW Statement: How to Use It and Best Practices

SQL views are incredibly valuable for database developers and administrators, offering a range of benefits to simplify complex tasks, enhance security, and improve overall workflow efficiency. You can use them to restrict data access, ensuring that sensitive information is protected while still enabling users to retrieve relevant data. Or, using SQL views, you can simplify the complexity of working with multiple tables and get a clean, unified interface without the need to dive into intricate join statements. Moreover, for users unfamiliar with SQL queries, views provide an easy way to access data without extra effort.

In this article, we’ll uncover the basics of the SQL CREATE VIEW statement, explore view types, and learn how to create a view in SQL, and how to query a view and drop it when you are done with it.

We’ll also explore the dbForge Edge’s capabilities in creating views through the visual View editor, which provides you with advanced features to create views, and explain how you can check views in your schema and refresh data. Let’s dive in!

Table of contents

• What is the SQL CREATE VIEW statement?
• Why use SQL views?
• How to create a view in SQL?
• How to query a SQL view?
• Types of SQL views
• Dropping a view in SQL
• How dbForge Edge simplifies SQL view management
• Conclusion

What is the SQL CREATE VIEW statement?

Generally speaking, in SQL, a view is a virtual table that provides a dynamic representation of data derived from one or more underlying tables. Unlike regular tables, views do not store data themselves. Instead, they generate the data every time they are accessed based on a query defined by you. This means that a view acts as an abstraction layer over complex data structures, making it easier for users to query and manipulate data without directly interacting with the base tables.

Mastering the SQL CREATE VIEW statement is the key to creating such virtual tables, which are becoming particularly useful in scenarios where you want to expose only specific data to users, improve security, or provide a more understandable way of accessing complex data.

Now, let’s break down what syntax is used to create a SQL view:

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

This code, when performed on your data, will let you select what columns to include into view based on certain conditions. 

For instance, let’s imagine we have a table with employees:

CREATE TABLE employees (
    employee_id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    department VARCHAR(50),
    salary DECIMAL(10, 2),
    hire_date DATE
);

This table stores information about employees, including their names, departments, salaries, and hire dates.

After we populate it with data, we are going to have the following structure:

employee_id	first_name	last_name	department	salary	hire_date
1	John	Doe	Engineering	75000	2015-03-25
2	Jane	Smith	Marketing	65000	2016-07-19
3	Tom	Johnson	Engineering	82000	2017-05-10
4	Emily	Davis	Sales	70000	2018-11-30
5	Michael	Brown	Engineering	90000	2019-01-15

Now, to better understand what is view in SQL, let’s imagine that, in some cases, the engineering department shouldn’t see salaries and employees related to other departments, as well as their colleagues’ salaries who earn more than a certain value. Thus, we’re going to create a view that shows only employees from the “Engineering” department with a salary of less than $80,000:

CREATE VIEW filtered_salary_engineers AS
SELECT employee_id, first_name, last_name, department, salary
FROM employees
WHERE department = 'Engineering' AND salary < 80000;

As a result, we get the following view:

employee_id	first_name	last_name	department	salary
1	John	Doe	Engineering	75000

As you can see, cheating views can simplify data access, letting you focus only on the data you need without worrying about the intricacies of the database schema and relationships, as well as provides that additional security by controlling access to specific rows and columns. Sensitive information can be hidden, while still allowing users to query non-sensitive data, ensuring a more secure environment.

Why use SQL views?

Whether you’re working with SQL Server, MySQL, Oracle, or PostgreSQL, SQL views offer significant benefits that can help streamline your database operations. Let’s explore the key advantages of using SQL views and how they contribute to better database management and security.

Specific data access restriction

One of the most significant benefits of using views is the enhanced security they provide. A view can be used to limit access to specific rows and columns of data in a table. This means you can present only the necessary information to users while hiding sensitive data. 

Simplification of complex queries

Views allow you to simplify complex queries by encapsulating complicated logic into a single object. Instead of repeatedly writing intricate JOIN, WHERE, or aggregate functions in every query, you can create a view that combines multiple tables or aggregates data.

Write once, use as long as it takes

Rather than repeating complex queries throughout your database, you can reference the same view whenever you need it. This reduces redundancy in your code and ensures that changes to the logic of a query only need to be made once, simplifying maintenance and updates.

Maintain logical data independence

Views provide you with a simplified, logical view of the data. This means the underlying schema or structure of the database can be kept hidden from the users. With views, you can easily partition data or present it in a specific format without changing the actual data structure. 

Performance considerations

While views are a powerful tool, it’s important to consider performance when using them. Since views don’t store data themselves, they generate the result set dynamically each time they are queried. Depending on the complexity of the view and the underlying query, this can sometimes lead to slower performance, especially with large datasets or complex joins.

How to create a view in SQL?

Since we have already learned how we can create a simple view from scratch, we’re already aware of how to start off. However, there’s even more to how to create view in SQL than you might think, especially when you need to add specific changes to it. Let’s check how you can use CREATE OR REPLACE VIEW statement to modify an existing view.

Here’s the query we’re going to use:

CREATE OR REPLACE VIEW filtered_salary_engineers AS
SELECT employee_id, first_name, last_name, department, salary, hire_date
FROM employees
WHERE department = 'Engineering' AND salary < 80000
  AND hire_date <= CURRENT_DATE - INTERVAL 3 YEAR;

This update modifies the high_salary_engineers view by:

• Adding a condition to filter employees who have been with the company for over 3 years.
• Including the hire_date column so users can see the hire date of the employees listed.

Here’s the expected output:

employee_id	first_name	last_name	department	salary	hire_date
1	John	Doe	Engineering	75000	2015-03-25

As you can see, creating and modifying views is extra simple, so you can change them whenever and however you need, extending the data available within a view or narrowing it down.

How to query a SQL view?

Once a SQL view is created, querying it is as simple as querying a regular table. A view acts as a virtual table that stores a predefined query, and you can interact with it just like any other database table.

To query a view, you simply use the SELECT statement, just as you would for any table. The key difference is that instead of accessing a physical table, you are retrieving data from the virtual structure defined by the view.

For example, let’s assume we have the filtered_salary_engineers view from earlier. Now, to retrieve data from this view, you can simply use a SELECT query:

SELECT * FROM filtered_salary_engineers;

This query retrieves all columns from the view: employee_id, first_name, last_name, department, salary, and hire_date, but only for employees from the “Engineering” department who earn less than $80,000 and have been with the company for more than 3 years.

Limitations of SQL views

While querying a view is simple, there are some limitations to be aware of.

Limitation	Explanation
No ORDER BY without LIMIT or TOP	In SQL, you cannot use an ORDER BY clause in a view unless you also use a limiting function like LIMIT (in MySQL and PostgreSQL) or TOP (in SQL Server). Views are designed to return data in an unordered manner, as they represent the underlying data dynamically. If you want to ensure the results are returned in a specific order, you’ll need to include the ORDER BY clause in the query, not in the view itself.
Views cannot be updated directly	Depending on the complexity of the view (e.g., if it includes multiple tables, aggregate functions, or joins), you may not be able to update the data directly through the view. In these cases, you would need to update the underlying tables directly.
Performance considerations	Since views are dynamically generated based on the underlying tables, large or complex views can have performance implications, especially if they are queried frequently.

Types of SQL views

There are several types of views, each serving a specific purpose depending on the complexity of the data and the query requirements. Let’s explore them further.

Simple views

A simple view is based on a single table and does not involve any complex functions, joins, or aggregations. It’s essentially a way to represent a subset of data from one table. Simple views are ideal when you just need to filter, restrict, or display a specific set of columns or rows.

Example

CREATE VIEW simple_employee_view AS
SELECT first_name, last_name, salary
FROM employees;

This view now presents a simplified view of the employees table, showing only the first_name, last_name, and salary columns. It’s easy to query and can be used when you want to make a table more accessible or reduce the complexity for users.

Complex views

A complex view involves multiple tables and may include joins, aggregate functions, or even subqueries. These views are used when you need to combine data from different tables, perform calculations, or filter data based on more intricate conditions.

To better understand how complex views work, let’s imagine that we have created two tables:

CREATE TABLE employees (
employee_id INT PRIMARY KEY,
first_name VARCHAR(50),
last_name VARCHAR(50),
department_id INT,
salary DECIMAL(10, 2),
hire_date DATE
);

CREATE TABLE departments (
department_id INT PRIMARY KEY,
department_name VARCHAR(50)
);

Here, one of the tables stands for employees’ data, and the other is for department ID and name, listing departments.

Here’s an example of how you can create a complex view with JOIN that lets you get data from the employees table and the departments table to calculate the average salary for each department. 

Example

CREATE VIEW department_salary_avg AS
SELECT d.department_name, AVG(e.salary) AS average_salary
FROM employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY d.department_name;

Complex views like this are useful when you need aggregated data across multiple tables.

Inline views

An inline view is a temporary result set that is used inside a query. These are also known as derived tables, as they’re created dynamically during the execution of a query. Inline views do not exist independently like regular views; they are part of the query itself.

Example

SELECT department_name, total_salary
FROM (
  SELECT d.department_name, SUM(e.salary) AS total_salary
  FROM employees e
  JOIN departments d ON e.department_id = d.department_id
  GROUP BY d.department_name
) AS department_totals;

In this case, the inline view (or derived table) is the subquery inside the FROM clause. It calculates the total salary per department, which is then used in the outer query. Inline views are useful when you need a temporary data set without creating a permanent view in the database.

Materialized views vs. standard views

SQL offers two types of views: standard views and materialized views. Each type serves a different purpose, and the choice depends on your use case.

Comparison	Materialized view	Standard view
Explanation	A materialized view stores data physically. It is essentially a snapshot of the result set returned by the query at the time the materialized view was created or last refreshed. Since the data is pre-stored, querying a materialized view is much faster than querying a standard view.	A standard view does not store any data. Instead, it is a virtual table that stores a query, and every time the view is queried, the database executes the underlying query to fetch the data. This approach provides real-time data but can be slower when querying large datasets since the query is executed on each request.
Syntax	CREATE MATERIALIZED VIEW department_salaries ASSELECT department_name, SUM(salary) AS total_salaryFROM employeesGROUP BY department_name;	CREATE VIEW employee_salaries ASSELECT first_name, last_name, salaryFROM employeesWHERE salary > 50000;
Use case	For improved performance for frequent queries on large datasets or need to store pre-aggregated results.	For real-time data, when you don’t mind the extra overhead of executing the query every time the view is accessed.

Dropping a view in SQL

Dropping a view can be useful when it is no longer necessary for your queries or when you need to clean up your database schema.This command allows you to delete a view without affecting the underlying tables or the data they contain. 

Here’s an example of syntax you can use to drop a view:

DROP VIEW [IF EXISTS] view_name;

For our previous view, the DROP VIEW example will look like this:

DROP VIEW filtered_salary_engineers;

Note that after executing this statement, the filtered_salary_engineers view will be removed from the database. As a result, any queries attempting to access this view will result in an error, as the view no longer exists.

How dbForge Edge simplifies SQL view management

When it comes to managing SQL databases, having the right tool can make all the difference. dbForge Edge is an advanced database management solution designed for SQL professionals, that comes with a comprehensive set of features that enhance the creation, modification, and management of SQL views. With its intuitive interface and powerful capabilities, dbForge Edge simplifies complex database tasks, making it easier to work with SQL databases across different DBMSs. With features like Visual Query Builder and Object Editor under the hood, dbForge Edge makes your experience with SQL views smoother across SQL Server, MySQL, and Oracle-powered databases.

How to create a view using dbForge Edge in a few clicks

Since dbForge Edge is a solution that covers several DBMSs, we’ll explore the process of creating views in SQL Server. 

1. To create a view, first access Database Explorer. 
2. Right-click the Views option and select New View.
3. Provide your view with a name and type a query that will represent the view.
4. Click Update Database to save the changes. 

Using views in dbForge Edge is also very simple. To get the data from a certain view, right-click a view in Database Explorer and press Retrieve Data in the menu that appears on your screen. After that, you’ll see all the data in a grid.

Conclusion

SQL views are a game-changer for anyone working with databases, from database administrators to analysts and developers. They simplify complex tasks, enhance security, and streamline everyday work. Whether you’re trying to protect sensitive data, simplify reporting, or boost your system’s performance, views make your life easier and your work more efficient. Feel free to explore what are views in SQL in practice, and try dbForge Edge for a sleeker experience with SQL syntax.

FAQ

What are the views in SQL?

Views in SQL are virtual tables created by a query that selects data from one or more underlying tables. They simplify complex queries and can provide an abstraction layer, making it easier to access data.

What is the difference between a view and a table in SQL?

A table stores actual data in the database, while a view does not store data but provides a dynamic representation of data from one or more tables based on a predefined query.

What is a view and types of views?

A view is a virtual table created by a query. Types of views include simple views (based on a single table, no functions or aggregations, complex views (aggregate multiple tables, use joins, and functions), inline views (temporary result sets used within a query), and materialized views (that store data and improve query performance by storing the results of a query).

What is the advantage of a view in SQL?

Views simplify complex queries, enhance security by restricting access to specific data, and provide data abstraction, making it easier to interact with the database without needing to understand its structure in detail.