Specifying NOT NULL Columns

Go Up to Defining Columns

You can optionally specify NOT NULL to force the user to enter a value. If you do not specify NOT NULL, then NULL values are allowed in the column. You cannot override a NOT NULL setting that has been set at a domain level with a local column definition.

Note

If you have already specified NULL as a default value, be sure not to create contradictory constraints by also specifying the NOT NULL attribute, as in the following example:

CREATE TABLE MY_TABLE (COUNT INTEGER DEFAULT NULL NOT NULL);