(Original) learning the Oracle View

-- View
-- A view is a logical table. It is used to view tables and define multiple connections between rows and columns from one or more tables. You can view the data in the table through the view.
-- Create a view
Create view mytest. v_info
(ID, name, loginname, address)
As
Select Test. ID, test. Name, test. loginname, info. Address from test, info where info. info_id = test. ID
-- View
Select * From v_info
-- Insert a column for the info table
Alter table info add Tel varchar2 (20 );
-- Modify View
-- There is no statement to modify the view separately. The statement used to modify a view is different from the statement used to create a view.
-- If you use create on replace view, the specified view must exist. Otherwise, the system will create the view.
Create or replace view mytest. v_info
(ID, name, loginname, address, TEL)
As
Select Test. ID, test. Name, test. loginname, info. Address, info. Tel from test, info where info. info_id = test. ID