> Can someone explain me why is it usefull if the table created in
> transaction disapears on rollback?
Because then you can write big scripts like we do at work to install a new
feature in the live database. Such a script might create two new tables,
add columns to existing tables, drop and recreate some foreign keys, etc.
What you do is to test it you go 'begin;' and then execute the script. If
it all worked, commit, else rollback and fix the script. Repeat until you
get it right.
Chris