How to Rename a Column in View in PL/SQL?

Renaming a column in a view can be a challenging task in PL/SQL, as the language does not provide a direct command for this operation. However, there are several effective methods to achieve this goal without compromising data integrity or the structure of the view.

In This article, we will explore three key approaches for recreating the view, using the ALTER VIEW statement, and using a temporary view. Through detailed examples and explanations learn how to rename a column in a view in PL/SQL efficiently and effectively.

Renaming Columns in View

• Changing the name of a column in a view is not as easy as changing the name of a column in a table.
• PL/SQL does not provide straightforward commands like RENAME COLUMN for views. However, there are several ways to do this which we are going to learn using the below methods.

Three Methods to Rename a Column in a View in PL/SQL

1. Recreating the View

The most common and easy method to rename a column in a view is to drop the existing view and recreate it with the new column name.

Example of Recreating the View

Here's an example showing how we can get this done. Let’s first create a sample table, products_data, to demonstrate this approach.

CREATE TABLE products_data (
    prod_code INT,
    prod_name VARCHAR2(50),
    prod_price NUMBER
);
INSERT INTO products_data (prod_code, prod_name, prod_price)
VALUES
    (101, 'Laptop', 50.00),
    (102, 'TV', 75.00),
    (103, 'Smartphone', 100.00);

Output:

Let's create an view called sales_view on which we will prfrom all the methods.

CREATE VIEW sales_view AS
SELECT prod_code, prod_name, prod_price
FROM products_data;

The problem is to rename the prod_code column in the sales_view to id without losing the data or the structure of the sales_view. Then displaying the contents of the "sales_view".

-- Drop the existing view
DROP VIEW sales_view;

-- Recreate the view with the new column name
CREATE VIEW sales_view AS
SELECT prod_code AS id,
       prod_name,
       prod_price
FROM products_data;
SELECT * FROM sales_view;

Output:

The Existing view "sales_view" is dropped and recreated with 'prod_code' being renamed to "id". And the content of newly created view is displyed.

2. Using the ALTER VIEW Statement

Another method to rename the column in view is by using the ALTER VIEW statement. Although, this is used less as compared to Recreating the view because it requires the view to be in a alterable state.

Example of Using ALTER VIEW

Here's an example showing the use of ALTER VIEW statement to alter the view:

-- Modify the view
ALTER VIEW sales_view AS
SELECT prod_code AS coupon_code,
       prod_name,
       prod_price
FROM products_data;
SELECT * FROM sales_view;

Output:

Here, ALTER VIEW statement will modify the 'sales_view' by changing the column named 'prod_code' to 'coupon_code'. Content of the altered view is displayed.

3. Using a Temporary View

Now, if there is a case arises where we are unable to directly drop the view, then we can create a temporary view with the our desired column name . After that, we can drop the original view and then rename our temporary view to the name of our original view.

Example of Using a Temporary View

Here's an example depicting the use of Temporary View:

-- Create a temporary view
CREATE VIEW temp_view AS
SELECT prod_code AS id,
       prod_name,
       prod_price
FROM products_data;

-- Drop the original view
DROP VIEW sales_view;

-- Rename the temporary view to the original view name
RENAME temp_view TO sales_view;
SELECT * FROM sales_view;

Output:

Here, view named "temp_view" is created with the new name of column named 'prod_code' as "id" . After that original "sales_view" is dropped, and then "temp_view" is changed to "sales_view". Content of updated "sales_view" is being displayed.

Conclusion

Renaming a column in a view in PL/SQL requires a strategic approach since direct renaming isn’t natively supported. By understanding these three effective methods—recreating the view, using ALTER VIEW (where possible), and utilizing a temporary view—you can handle column renaming in views efficiently and without data loss.

These techniques not only help in maintaining a clean, well-structured database but also enhance the flexibility and readability of your database schema, making it easier to meet business requirements and adapt to evolving naming conventions.