SQL trigger
An SQL trigger is a database routine or object that executes automatically in response to specified events on a database object.
MongoDB 8.0 in Action, Third Edition
A database trigger responds to changes in database data, such as modifications to documents in a collection.
- How it is used
- Uses database triggers to automate responses to collection changes and enforce business rules without manual intervention.
- How deep it goes
- Explains event-to-function flow and setup controls, but provides no SQL trigger statements or SQL-dialect implementation.
- Examples
- Illustrates related-record updates, inventory adjustments, document embeddings, and a function that logs change events.
- What you can do after
- Operate/configure it in Atlas by selecting a database trigger, setting its controls, and connecting an event-handling function.
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Just Use Postgres!
A database trigger is a stored procedure that the database automatically executes in response to specified events on database objects.
- How it is used
- Automates derived-data maintenance inside the database when application data changes.
- How deep it goes
- Explains trigger functions, event binding, row-level execution, and NEW/OLD records without deeper administration guidance.
- Examples
- Demonstrates order-item changes, recalculated pending totals, NEW and OLD records, and checkout output.
- What you can do after
- Operate/configure PostgreSQL triggers that recalculate derived order data after row changes.
PostgreSQL Mistakes and How to Avoid Them
A database trigger is a routine that executes automatically in response to specified events on a database object.
- How it is used
- Provides predictable database-side responses to table changes where PostgreSQL rule rewriting creates dangerous side effects.
- How deep it goes
- Contrasts trigger predictability with rule rewriting, repeated VOLATILE calls, and updates that still execute; it does not implement trigger syntax.
- Examples
- Uses order insertion auditing and an old-order update rule to expose unintended effects and misleading prevention.
- What you can do after
- Evaluate when a PostgreSQL trigger is safer than a rule for predictable database-side behavior.
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Build Financial Software with Generative AI (From Scratch)
A database trigger is database code that executes automatically in response to specified database events.
- How it is used
- Uses automatic database events to consider keeping parsed and unparsed ACH records synchronized during deletion.
- How deep it goes
- Defines triggers and sketches a deletion use case, but stops short of implementation details or executable trigger code.
- Examples
- Considers deleting an associated unparsed ACH record when its parsed record is deleted.
- What you can do after
- Evaluate trigger-based cleanup against application logic and table restructuring when preserving related records.
Read how Build Financial Software with Generative AI (From Scratch) explains SQL trigger →
Related concepts
- databaseuses · A database is an organized collection of persistent data managed by software for storage, retrieval, querying, and modification.
- rulealternative to · A PostgreSQL rule is a query-rewrite definition attached to a database relation that modifies or adds statements when specified events occur.
- triggerkind of · A trigger is an event, condition, input, or schedule that causes or signals an action, process, or state transition to begin or proceed.
- auditabilityalternative to · Auditability is the ability to trace, inspect, and verify a system’s actions, decisions, changes, or records using available evidence.
- denormalizationused by · Denormalization is the deliberate combination or duplication of related data to simplify access, support particular access patterns, or improve performance.
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