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  1.  Home
  2. MIDRANGE-L
  3. February 2016

NOT NULL WITH DEFAULT ... Create vs. Alter

Folks:

I've observed something interesting recently.

If you create a table with a field that's specified as 'NOT NULL', the table will be created fine.

CREATE TABLE TEST1 (F1 CHAR (10) NOT NULL)

If you try to ADD a column to that table with a field that's also specified 'NOT NULL', the column WILL NOT be added because it lacks a default value.

ALTER TABLE TEST1 ADD COLUMN F4 CHAR (10) NOT NULL
NOT NULL clause not allowed.

If you specify a implicit or explicit default value for the column, the column will be created fine.

ALTER TABLE TEST1 ADD COLUMN F4 CHAR (10) NOT NULL WITH DEFAULT
ALTER completed for table TEST1.

Any idea why the table can be created without a default value on the column but can't be altered in the same way?

As a side note, at least on 6.1, if you specify a CCSID value on the add column statement, the lack of a default value does not generate an error.

ALTER TABLE TEST1 ADD COLUMN F4 CHAR (10) NOT NULL CCSID 37
ALTER completed for table TEST1

david




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