>The default constraint was the one preventing the executuon of the DROP COLUMN. I now realized it myself, you do need to drop all constraints referecing the field prior to dropping the field.

Those that were causing me problems was because they have been created with the DEFAULT WITH VALUES clauses. All the fields that are created from the framework have a default values in the existing records (a blank value), in order to avoid NULL everywhere. Those that were created before do not have any constraint related to them. So, that explains it all. I have found a SQL that list the constraint for a column. Then, if one is found, I will remove it before proceeding. That will resolve the issue.

Thanks