How to fix the Oracle error PLS-00366: subtype of a NOT NULL type must also be NOT NULL?

In this post, you’ll learn more about the Oracle ErrorPLS-00366: subtype of a NOT NULL type must also be NOT NULL with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

PLS-00366: subtype of a NOT NULL type must also be NOT NULL

Reason for the Error PLS-00366: subtype of a NOT NULL type must also be NOT NULL

After a subtype was defined as NOT NULL, it was used as the base type for another subtype defined as NULL. That is not allowed. For example, the code might look like DECLARE SUBTYPE Weekday IS INTEGER NOT NULL; SUBTYPE Weekend IS Weekday NULL; — illegal instead of DECLARE SUBTYPE Weekday IS INTEGER NOT NULL; SUBTYPE Weekend IS Weekday;

How to fix the Error PLS-00366: subtype of a NOT NULL type must also be NOT NULL ?

You can fix this error in Oracle by following the below steps

Revise the subtype definitions to eliminate the conflict.