Are triggers executed with the current transaction isolation level?

Don't use triggers for such validation. Triggers don't scale. Also, as you have noticed they don't work in multi-user environments.

This is why Nature gave us unique constraints.

Don't use triggers for such validation. Triggers don't scale. Also, as you have noticed they don't work in multi-user environments.

This is why Nature gave us unique constraints. Alter table your_table add constraint yr_tab_uk unique (category, code) using index.

3 +1: use constraints instead of triggers whenever possible. In that case anyway, the trigger wouldn't be able to query the base table, since this would raise a MUTATION error (ORA-4091). – Vincent Malgrat Aug 31 '09 at 9:38.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.