In this section, we will look at
- What is a trigger and how it works
- When to use triggers?
- Examples of triggers
PostgreSQL Triggers are database callback functions, which are automatically performed/invoked when a specified database event occurs.
PostgreSQL trigger can be specified to fire on three different scenarios.
Before the operation is attempted on a row (before constraints are checked and the INSERT, UPDATE or DELETE is attempted)
After the operation has completed (after constraints are checked and the INSERT, UPDATE, or DELETE has completed)
Instead of the operation (in the case of inserts, updates or deletes on a view)
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