> 1) Is it possible to disable a trigger, or do I have to drop it?
> If the later (dropping it), how can I get the trigger to reinstate it
> after I am done with my update?

You can use the ALTER TRIGGER <triggername> INACTIVE

However, you need to commit it separately. I don't recommend you do it this
way. You will run out of metadata versions and have to backup and restore
your database.

> 2) How can I set a generator's value?

Use the GEN_ID() method and set the increment accordingly. You can use
negative increment values. I sense you are trying something that may be
better done a different way. You may want to tell us more about what you are
up to.

Jason Wharton