A default value control phrase determines the action to take when you do not supply a value for a field.
The following rules and guidelines apply to default value control phrases:
- Default value control phrases are only valid with the following data definitions.
- Fields defined in CREATE TABLE and ALTER TABLE statements
- Parameters defined in CREATE MACRO and REPLACE MACRO statements
- Default value controls are not effective for views and expressions.
- The default value for a field is null unless you specify NOT NULL, in which case there is no default value if you do not specify the DEFAULT phrase.
- The presence of nulls can affect query performance negatively; therefore, consider using the NOT NULL default value phrase unless you intend to have nulls in the column.