Views

Simple views

A view can filter some rows from the base table or project only some columns from it:

CREATE VIEW new_employees_details AS
SELECT E.id, Fname, Salary, Hire_date
FROM Employees E
WHERE hire_date > date '2015-01-01';

If you select form the view:

select * from new_employees_details

Id	FName	Salary	Hire_date
4	Johnathon	500	24-07-2016

Complex views

A view can be a really complex query(aggregations, joins, subqueries, etc). Just be sure you add column names for everything you select:

Create VIEW dept_income AS
SELECT d.Name as DepartmentName, sum(e.salary) as TotalSalary
FROM Employees e
JOIN Departments d on e.DepartmentId = d.id
GROUP BY d.Name;

Now you can select from it as from any table:

SELECT * 
FROM dept_income;

DepartmentName	TotalSalary
HR	1900
Sales	600