DEFINE

DEFINE is a SQL*Plus command used in Oracle database systems to set a variable to a specific value. In SQL scripts, these variables can later be referenced for performing actions on a database.

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.

For in-depth explanations and examples SQL keywords where you write your SQL, install our extension.