DB2 Modifying a table field

1: Delete field non-empty property

ALTER TABLE XXX ALTER COLUMN XXX drop NOT NULL

This feature requires a version of DB2 9.0 or more

2: Add field non-empty property
ALTER TABLE XXX ALTER COLUMN XXX set NOT NULL

3: Add a new field
ALTER TABLE XXX add column XXXX varchar (100)

4: Delete a field
ALTER TABLE XXX drop column XXX

5: Increase the length of the field
ALTER TABLE XXX ALTER COLUMN XXX SET data type varchar (100)

Attention:

1: The name of the field is not allowed to be modified (can only be deleted first and then added).

2: The length of the field is not allowed to be reduced.

3: Modification of the field type is not allowed (such as modifying Integer to varchar).

4: If you have to modify the situation in the previous three, you can only re-build the table (the first one has a simple method).

DB2 Modifying a table field