15.10 - Using Default Value Control Phrases - Teradata Database

Teradata Database SQL Data Types and Literals

Teradata Database
Programming Reference

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.
  • The default control value phrases are documented individually in the remaining topics in this chapter.