DEFINE

Oracle

Example

DEFINE customer_id = 10;
SELECT * FROM customers WHERE id = &customer_id;
UNDEFINE customer_id;

Output

id	first_name	last_name	email
10	John	Doe	john.doe@example.com

Explanation

In the example, the DEFINE command is used to create a substitution variable named customer_id with a value of 10. This substitution variable is then referenced in the SELECT statement using an ampersand & just before the variable name to retrieve the customer record with id 10. The UNDEFINE statement at the end removes the substitution variable.