A default value control phrase determines the action to take when you do not supply a value for a field.
Rules and Guidelines
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.
The default control value phrases are documented individually in the remaining topics in this section.