Making Changes to Columns | ALTER TABLE | Teradata Vantage - 17.10 - Changing Column Attributes: NOT NULL or NULL - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Data Definition Language Detailed Topics

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1184-171K
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