Oracle View

In Oracle, view is a virtual table that does not physically exist. It is stored in Oracle data dictionary and do not store any data. It can be executed when called.

A view is created by a query joining one or more tables.

Oracle CREATE VIEW

Syntax:

CREATE VIEW view_name AS  

SELECT columns  

FROM tables  

WHERE conditions;  

Parameters:

• view_name: It specifies the name of the Oracle VIEW that you want to create.

Example:

Let’s take an example to create view. In this example, we are creating two tables suppliers and orders first.

Suppliers table:

   CREATE TABLE  "SUPPLIERS"  

   (    "SUPPLIER_ID" NUMBER,   

    "SUPPLIER_NAME" VARCHAR2(4000),   

    "SUPPLIER_ADDRESS" VARCHAR2(4000)  

   )  

/   

Orders table:

CREATE TABLE  "ORDERS"   

   (    "ORDER_NO." NUMBER,   

    "QUANTITY" NUMBER,   

    "PRICE" NUMBER  

   )  

/ 

Execute the following query to create a view name sup_orders.

Create View Query:

CREATE VIEW sup_orders AS  

SELECT suppliers.supplier_id, orders.quantity, orders.price  

FROM suppliers  

INNER JOIN orders  

ON suppliers.supplier_id = supplier_id  

WHERE suppliers.supplier_name = 'VOJO'; 

Output:

View created.
0.21 seconds

You can now check the Oracle VIEW by this query:

SELECT * FROM sup_orders;  

Output:

SUPPLIER_ID	QUANTITY	PRICE
  3	         35	          70
  3	         26	         125
  3	         18	         100
3 rows returned in 0.00 seconds

Oracle Update VIEW

In Oracle, the CREATE OR REPLACE VIEW statement is used to modify the definition of an Oracle VIEW without dropping it.

Syntax:

CREATE OR REPLACE VIEW view_name AS  

  SELECT columns  

  FROM table  

  WHERE conditions; 

Example:

Execute the following query to update the definition of Oracle VIEW called sup_orders without dropping it.

CREATE or REPLACE VIEW sup_orders AS  

  SELECT suppliers.supplier_id, orders.quantity, orders.price  

  FROM suppliers  

  INNER JOIN orders  

  ON suppliers.supplier_id = supplier_id  

  WHERE suppliers.supplier_name = 'HCL'; 

You can now check the Oracle VIEW by this query:

SELECT * FROM sup_orders;  

Output:

SUPPLIER_ID	QUANTITY	PRICE
      1	         35	         70
      1	         26	        125
      1	         18	        100
row(s) 1 - 3 of 3		

Oracle DROP VIEW

The DROP VIEW statement is used to remove or delete the VIEW completely.

Syntax:

DROP VIEW view_name;  

Example:

DROP VIEW sup_orders;