The following rules apply to the use of the DEFAULT function as part of a RESET WHEN condition:
- You can specify a DEFAULT function with a column name argument within a predicate. The system evaluates the DEFAULT function to the default value of the column specified as its argument. After evaluation, the DEFAULT function is treated like a literal in the predicate.
- You can specify a DEFAULT function without a column name argument within a predicate only if there is one column specification and one DEFAULT function as the terms on each side of the comparison operator within the expression.
- Following existing comparison rules, a condition with a DEFAULT function used with comparison operators other than IS [NOT] NULL is unknown if the DEFAULT function evaluates to null.
A condition other than IS [NOT]NULL with a DEFAULT function compared to a null evaluates to unknown.
| Clause | Comparison Result |
|---|---|
| IS NULL | TRUE if the default is null, otherwise FALSE. |
| IS NOT NULL | FALSE if the default is null, otherwise TRUE. |