16.20 - Changing Column Attributes: NOT NULL or NULL - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantage™ SQL Data Definition Language Detailed Topics

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Release Date
March 2019
Content Type
Programming Reference
Publication ID
B035-1184-162K
Language
English (United States)

When changing columns from NULL to NOT NULL, or from NOT NULL to NULL, refer to the following table:

Column Attribute Composite Changes
NULL Not permitted.
NOT NULL Permitted.

The following rules define how columns defined with NULL or NOT NULL attributes can be altered:

This column type … When defined as … Can be altered to this column type …
Indexed NULL NULL only
NOT NULL NOT NULL only
Unindexed NULL NOT NULL

If and only if the column does not contain nulls.

NOT NULL NULL