[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] UNION keyword  union queries, folding data  unions, sets  universes, sets      comparing sets with universe      complement  UPDATE statement     audit-log space consumption      log triggers      row-level logs      sets and  UPDATE trigger, master records online