If you have worked with SQL before, you may have used various complex queries. When it comes to easier data management, "views" in SQL can be a very helpful tool. Simply put, a view is like a virtual table that allows us to see query results as if they were a table, without needing to store these results permanently.
Imagine you have various pieces of data from multiple tables that you want to combine into a specific report. This query may be quite complex, and each time you write it, it can be time-consuming and complicated. Views enable you to define this complexity once and have direct access whenever needed with a simple command using the same data.
Views can also help hide complex queries from users. Essentially, they allow user access to certain data without the need for them to understand the complete structure of the underlying table and relationships. This way, security and control over data will be significantly enhanced.
Over time, the original table structure might change, but views can still act as a persistent interface, maintaining continuity. This is especially important for large projects that require maintenance and changes, making views highly effective. Views can prevent structural changes from impacting directly on your queries and are great for decoupling the main data structure from the applications that use them.
Many experts believe that the performance and operational capabilities of views are often superior to standard tables. However, this does require adequate time to assess their use within database management systems.
SQL Code Example for Creating and Using Views
CREATE VIEW employee_view AS
SELECT employee_id, first_name, last_name, department
FROM employees
WHERE active = 1;
SELECT * FROM employee_view;Line-by-Line Explanation of the Code
CREATE VIEW employee_view AS: Creates a view named employee_view that functions as a virtual table.
SELECT employee_id, first_name, last_name, department: Selects the columns you want to appear in your view.
FROM employees: Uses the employees table as the source for the data.
WHERE active = 1;: A condition that only includes currently active employees.
SELECT * FROM employee_view;: Retrieves all data from the defined view that has been created.