Following existing comparison rules, a condition with a DEFAULT function used with comparison operators other than IS NULL or IS NOT NULL is unknown if the DEFAULT function evaluates to null.
A condition other than IS NULL or IS NOT NULL with a DEFAULT function compared with a null evaluates to unknown.
|IF a DEFAULT function is used with …||THEN the comparison is …|
|IS NOT NULL||
For more information about the DEFAULT function, see Teradata Vantage™ - SQL Functions, Expressions, and Predicates, B035-1145.