A view is a virtual table based on the result of a query. Similar to a real table, it contains rows and columns. The fields in a view can either be calculated fields or correspond to fields from one or more real tables in the database.
CREATE VIEW statement is used to create a view. Utilizing views can simplify complex queries, hide the complexity of data, and control the data visibility for users. In Polypheny, views also provide a convenient way to make data represented using one data model accessible in another namespace.
The basic syntax for a
CREATE VIEW statement in Polypheny is:
CREATE VIEW view_name [ (column1, column2, ... ) ] AS query
view_name: Specifies the name of the view. The name must be unique within the namespace.
column1, column2, ...: Optional list of names for the columns in the view. If provided, the number of names must match the number of columns returned by the
query: An SQL query that defines the view. This can be any valid SELECT statement that retrieves data from tables in the database.
If the optional column list (
column1, column2, ...) is provided, it must match the number and order of the columns returned by the
query. These column names are then used as the column names of the view.
Here is an example of a
CREATE VIEW statement:
CREATE VIEW employee_view AS SELECT first_name, last_name FROM employees WHERE salary > 50000
In this example, a view named
employee_view is created. This view presents the first name and last name of employees whose salary exceeds 50000. By using the
CREATE VIEW statement, this query is saved and can be easily executed with the
SELECT * FROM employee_view command.