CREATE TABLE customers ( id INTEGER PRIMARY KEY, FirstName TEXT NOT NULL, LastName TEXT NOT NULL, PhoneNumber TEXT NOT NULL, Extension TEXT

); -- insert some values INSERT INTO customers VALUES (1, 'Hxxx', 'Rxx', '1', NULL); INSERT INTO customers VALUES (2, 'Lxx', 'Fxxx', '2', NULL); INSERT INTO customers VALUES (3, 'Micxx', 'Sax', '3', '12'); INSERT INTO customers VALUES (4, 'Minxxx', 'H..', '4', '77'); INSERT INTO customers VALUES (5, 'Sxx', 'Stxxx', '5', NULL); -- fetch some values --SELECT * FROM customers; --SELECT * FROM customers where Extension is not NULL; SELECT * FROM customers where Extension is not NULL order by LastName;

• • create a table CREATE TABLE students ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, gender TEXT NOT NULL ); -- insert some values INSERT INTO students VALUES (1, 'Ryan', 'M'); INSERT INTO students VALUES (2, 'Joanna', 'F'); -- fetch some values -- SELECT * FROM students WHERE gender = 'F';

create view games as select * from students;

select * from games;

SQL CREATE VIEW Statement

In SQL, a view is a virtual table based on the result-set of an SQL statement.

A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.

You can add SQL statements and functions to a view and present the data as if the data were coming from one single table.

A view is created with the CREATE VIEW statement.

A view

• is a virtual table
• contains rows and columns
• contains just like a real table. (Just like可以作为介词，表示“像……一样，就像……一样”，后接名词或代词作为宾语。 例如： 1）She looks just like her mother. 她看起来和她妈妈一模一样。)