Web Dev//SQL//trigger

Code that runs automatically when something happens in a table. You don't call it — the database calls it for you.

Code that runs automatically when something happens in a table. You don't call it — the database calls it for you.

Fires on INSERT, UPDATE, or DELETE. Can run BEFORE or AFTER the event.

Example: Roberto's apartment is sold → a trigger automatically invalidates all his matches. Zero extra code needed in the backend.

A trigger is a function (CREATE FUNCTION) + a binding (CREATE TRIGGER ... ON table). The function defines the logic, the binding defines when it fires.

In Supabase, triggers are created in the SQL Editor. The Table Editor can't touch them — it only shows rows.

The invisible automation layer: triggers are one of the things that make a database more than a spreadsheet. The data reacts to itself.