Salesforce DictionarySalesforce DictionarySalesforce DictionarySalesforce DictionaryDeclarative data quality vs programmatic logic
A Validation Rule in Salesforce is a formula that the platform evaluates every time a user saves a record. If the formula returns true, the save fails and the rule's error message displays to the user. Validation Rules are how Salesforce admins enforce data quality at the record-save layer: the rule checks that required-conditional fields are populated, that date relationships make sense, that picklist values are consistent, that custom business logic holds. Every object in Salesforce can have its own set of Validation Rules, and each rule runs independently on save. Validation Rules sit at one end of the data-quality enforcement spectrum, with Required-on-Page-Layout at the other. Required fields fire a simple "this field is blank" error; Validation Rules fire on any condition you can express in a formula, which means almost anything a record could violate. The cost of that flexibility is performance and maintenance: each Validation Rule adds save-time work, and a record save that fails a Validation Rule produces an error that needs to be readable enough for the user to fix the underlying issue. Orgs that accumulate fifty Validation Rules per object usually find half of them firing on edge cases nobody anticipated.
An Apex trigger is a block of Apex code that runs automatically when records on a specific object are inserted, updated, deleted, or undeleted. It is the platform's primary hook for executing custom logic in response to data changes, and it has been the workhorse of programmatic Salesforce automation for fifteen years. Triggers fire at two timing points (before and after the database operation) for each of the four DML events, producing seven possible trigger contexts on each object. A trigger is declared with the trigger keyword, a name, an object reference, and one or more event contexts: trigger AccountTrigger on Account (before insert, after insert, before update, after update). Inside the trigger, the Trigger.new, Trigger.old, Trigger.newMap, and Trigger.oldMap context variables expose the records being processed. Most production triggers delegate immediately to a handler class for the actual logic, keeping the trigger file as a thin dispatcher. This pattern (the Trigger Handler) is the foundation of every maintainable Apex codebase.
| Dimension | Validation Rule | Apex Triggers |
|---|---|---|
| Approach | Declarative - formula-based | Programmatic - Apex code |
| Purpose | Enforce data quality before save | Complex business logic on record events |
| Timing | Before save only | Before and after insert, update, delete, undelete |
| Complexity | Single formula expression | Full programming language capabilities |
| Error Handling | Displays error on field or page top | Can throw custom exceptions and log errors |
Simple data quality checks like required fields, format validation, or cross-field rules.
Complex business logic, cross-object updates, or integrations triggered by record events.
Other side-by-side breakdowns you might find useful