In SQL, a view is a virtual table that is based on the result of an SQL query. Views can simplify complex queries, as they allow you to abstract away the complexity and present the results in a more straightforward way. In this blog post, we will explore how to create views using the SQL command-line interface (CLI).

Step 1: Connect to the Database

Before creating a view, you need to connect to your database using the SQL CLI. Depending on the database system you are using, the command to connect may vary. For example, to connect to a MySQL database, you can use the following command:

mysql -u <username> -p

After executing this command, you will be prompted to enter your password.

Step 2: Create a View

Once you are connected to the database, you can proceed to create a view. The syntax for creating a view in SQL is as follows:

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

Let’s say we have a table called “employees” with columns “name”, “age”, and “salary”. To create a view that only includes the names and salaries of employees aged 30 or above, you can use the following SQL command:

CREATE VIEW senior_employees AS
SELECT name, salary
FROM employees
WHERE age >= 30;

Step 3: Query the View

Once the view is created, you can query it just like any other table. For example, to retrieve the names and salaries of senior employees from the “senior_employees” view, you can use the following SQL query:

SELECT name, salary
FROM senior_employees;

Step 4: Update the View (Optional)

Views are dynamic, meaning they update automatically when the underlying data changes. However, you can also manually update a view if needed. To update the definition of a view, you can use the CREATE OR REPLACE VIEW statement. For example, to update the “senior_employees” view to include employees aged 35 or above, you can use the following SQL command:

CREATE OR REPLACE VIEW senior_employees AS
SELECT name, salary
FROM employees
WHERE age >= 35;

Conclusion

Creating views in SQL CLI can greatly simplify querying complex data and make your code more maintainable. By abstracting away the underlying complexity, you can focus on accessing and analyzing the data in a more straightforward manner. So next time you find yourself writing a complex query, consider creating a view instead!