What is Trigger?

What is a Trigger?

A trigger starts another action automatically when a defined event occurs in a system. The event may be a form submission, database insert, file upload, successful payment, or scheduled time.

Types

Triggers are used at different layers:

• Database trigger: Writes an audit record after an INSERT, UPDATE, or DELETE.
• Application trigger: Starts email, invoice, or stock logic after an order is created.
• Webhook trigger: Runs an integration flow after an external system sends an event.
• Time trigger: Starts report generation or data synchronization at a set time.

What to Watch For

Triggers can create invisible side effects, so they should be logged, authorized, and designed to be idempotent when possible. The same event arriving twice may produce duplicate invoices, repeated notifications, or incorrect stock changes.

In event-driven architectures, a trigger often starts the event flow. A cron job is a time-based trigger rather than an event-based one.