DEFAULT Function Comparison Operators - Teradata Database

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 NULL	TRUE if the default is null Else it is FALSE
IS NOT NULL	FALSE if the default is null Else it is TRUE

For more information about the DEFAULT function, see SQL Functions, Operators, Expressions, and Predicates.