The general rule for managing nulls with DateTime and Interval data environments is that, for individual definitions, the rules are identical to those for handling numeric and character string values.
| Type of Expression with NULL Component | Result |
|---|---|
| Value | NULL |
| Conditional | FALSE |
| CASE | As for any other CASE expression |
DateTime or Interval values are defined to be either atomically null or atomically non-null. For example, you cannot have an interval YEAR TO MONTH value in which YEAR is null and MONTH is not.