How does Validation Rule work in Salesforce?
Validation rules evaluate a Boolean formula each time a record is saved. If the formula returns true, the save is blocked and a custom error message is displayed, either at the top of the page or next to a specific field. This mechanism enforces data quality at the platform level, catching issues that page layouts and required fields alone cannot address, such as conditional requirements (e.g., Discount Reason is required when Discount exceeds 20%).
Validation rules fire for all save operations: UI edits, API calls, Data Loader imports, and Apex DML. This universality is powerful but demands careful design; overly aggressive validation rules can break integrations or block legitimate bulk operations. Admins should include bypass mechanisms (e.g., a custom permission or hierarchy custom setting) for integration users and data migration scenarios. Clientell AI can generate validation rule formulas from natural language descriptions and test them against sample data before deployment.