You can add columns to a table only if you created the table or are specifically authorized to do so.
The new column is initially generated with null values. Use the UPDATE statement to provide actual values for the new column.
ALTER TABLE PERS ADD PHONENO SMALLINT
In Db2® for Linux®, UNIX, and Windows, you can define a column as NOT NULL WITH DEFAULT, but you cannot define an added column to be NOT NULL.
NOT NULL WITH DEFAULT is invalid when your current location is a DB2® Server for VSE and VM.