Some prickly problems

Overcoming the limitations of views Triggers, function, and rules Trigger is a type of function Cannot update a view Can use rules

CREATE OR REPLACE RULE "txnview_update" AS
  ON UPDATE TO txnview
  DO INSTEAD
  SELECT myfunc();

CREATE OR REPLACE RULE "txnview_update" AS
  ON INSERT TO txnview
  DO INSTEAD
  INSERT INTO txn (id) VALUES (NEW.id);

CREATE OR REPLACE RULE "txnview_update" AS
  ON INSERT OR UPDATE OR DELETE TO txnview
  DO INSTEAD
  SELECT 'No changes made. No update, delete, or insert allowed.' AS "Warning!";

oscon=> UPDATE txnview SET price = price + 1 WHERE id=123;
                     Warning!
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No changes made. No update, delete, or insert allowed.