force inclusion of certain fields in update (trigger?)

Problem:

A table TABLE1 has 3 columnns:
  id number,
  text varchar(20),
  username varchar(10)

Each time a row is updated, I want to force the user to include his username in the update.

The following update would be illegal and should be rejected:

  update TABLE1
  set text='new text'
  where id=1;

Whereas the following update would be legal:

  update TABLE1
  set text='new text', username='alex'
  where id=1;

More precisely, table1 is a config table which is only updated manually and never by a program. So when a user updates this config table, I want to make sure that the field "username" contains the username of this updating user. Surely, I cannot force the user to include his *correct* name, he could be faking, but the point is just that I want to FORCE him to include the field username at all!

How can this be achieved?

Idea: in a trigger on the table TABLE1 a la:

  if inserting then
    if :new.username is null then

• do something ugly, e.g. throw an exception end if elsif updating then if ?????? then -- test whether the update field list
  • contains the field "username"
• do something ugly, e.g. throw an exception end if end if

So, how can the ?????? be solved?

Any ideas?

TIA,
Alex Received on Thu Feb 21 2002 - 04:02:28 CST