View Information

DESCRIBE user_views;

  - To check the construction of the user_views.

Name	Null?	Type
VIEW_NAME	NOT NULL	VARCHAR2(30)
TEXT_LENGTH		NUMBER
TEXT		LONG
TYPE_TEXT_LENGTH		NUMBER
TYPE_TEXT		VARCHAR2(4000)
OID_TEXT_LENGTH		NUMBER
OID_TEXT		VARCHAR2(4000)
VIEW_TYPE_OWNER		VARCHAR2(30)
VIEW_TYPE		VARCHAR2(30)
SUPERVIEW_NAME

SELECT DISTINcT view_name FROM user_views;

 

VIEW_NAME
EMPLOYEES_VU
DEPT50

SELECT text FROM user_views WHERE view_name = 'DEPT50'

TEXT
select employee_id, last_name, department_id from employees where department_id

  - The TEXT column saves a SELECT statement that is used to create a view and its datatype is LONG.
  - By default, it shows only 80 characters. If more characters are required, user the command : SET LONG
  ex) SET LONG 1000

** Data Access Using Views
When you access data using a view, the Oracle server performs the following operations:

• It retrives the view definition from the data dictionary table USER_VIEWS.
• It checks access privileges for the view base table.
• It converts the view query into an equivalent operation on the underlying base table or tables. In other words, data is retrived from, or an update is made to, the base tables.