PostgreSQL - UPDATE

UPDATE

-- simple UPDATE
UPDATE stock SET retail=25.95 WHERE isbn='0590445065';

-- updaing entire columns
UPDATE stock SET retail=(cost*((retail/cost)+0.1::numeric));

-- updating several columns
UPDATE publishers SET name='O\'Reilly & Associates', address='O\'Reilly & Associates, Inc. 101 Moriss St, Sebastopol, CA 95472' WHERE id=113;

-- update with several sources
UPDATE stock SET retail=stock_backup.retail FROM stock_backup WHERE stock.isbn=stock_backup.isbn;