Praktische triggers en audit

Now that we've learned how to forge smart bullets (the Trigger Functions), we need to mount them on real Primed Weapons waiting for an event: here come the actual Triggers! A trigger formally attaches a previously created function and instructs it to fire "BEFORE" or "AFTER" a particular CRUD event on a given table.

There are many options; for example FOR EACH ROW fires it once per affected row, so if a bulk query is a GLOBAL UPDATE over 5 million rows, it would fire 5 million micro-executions — be careful with that!

CREATE TRIGGER sync_inventory_trigger
-- Event options
AFTER INSERT OR UPDATE ON order_items
-- Modus operandi (singular or global macro-block FOR EACH STATEMENT)
FOR EACH ROW
-- Run the forged action
EXECUTE FUNCTION update_stock();

The trigger is invisible to JavaScript and will autonomously keep the stock perfectly consistent based strictly on updates submitted safely to the engine.

Automating Updated_At

There is an evergreen business problem where we forget to pass { updated_at: new Date() } in our JS update models. A trigger function set_updated_at combined with a BEFORE UPDATE trigger removes this nuisance, silently updating every record change autopoietically.

Try it yourself