a wrote: > What I want is to add a log entry at the last column of each row, which will record the > history update, insert automatically when relative statement is processed. > > I have read the documentation on triggers, which helps a lot. However, I may have few > more extra requirement to complete my wishes: > > 1, I would like to get the username of who executed the statement; > > 2, I would like to get the column name that is being updated; > > If it is possible and how should I do it?? You could use the "current_user" function to get the current user. Mind, however, that updates caused by a cascading update from a foreign key constraint will be executed as the owner of the table, so it would be better to use "session_user" to avoid surprises. You cannot get the column name, because PostgreSQL updates a whole row, not an individual column. The best you can do is to check which column values are different in OLD and NEW. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com
