Database manager generates value

Use this option to allow the Database manager to generate values for the column. This option is valid only when the column is an identity column or if the data type is ROWID. Possible values are:

Always
Specifies that the database manager will always generate a value for the column when a row is inserted into the table. ALWAYS is the recommended value.

By default
Specifies that the database manager will generate a value for the column when a row is inserted only if a value is not specified for the column. If a value is specified, the database manager uses that value. The value that is specified must be valid for the data type.