About database view

can you please refer to the following article.

www.javatpoint.com/mysql-view

super short: it is a "view" of specific wanted values of two or more DB tables joined by common attributes.

Example:

Table "Office" with columns
Id, office name, addressId, employeeCount,...
table "address" with columns
Id, post code, city, street, house number


you can join then via office.addressId - adress.id fields so a "unique conneciton" is possinle.
your view CAN have the following columns then: 
OfficeId, officeName, post code, city, street, house number

mad by an join SQL statement https://www.w3schools.com/sql/sql_join.asp

used in Appian context: performance improvements (DB joins are faster), more smaller tables instead of view big tables with redundant data but with view they can be connected easily.

The view is virtual table created from the base table and they don't have physical existence in the database. it contains rows and columns like a real table.

views are used for security purpose, for ex. u have a data of US employee like emp_id, emp_name, emp_department and their emp_SSNNo.....now u dont want to show the SSN number to the user u can hide it using views means u are keeping it secure and hiding confidential info.