Triggers and Order of Execution

When you save a record with an insert, update, or upsert statement, Salesforce.com performs the following events in order.
Note
Before Salesforce.com executes these events on the server, the browser runs JavaScript validation if the record contains any dependent picklist fields. The validation limits each dependent picklist field to its available values. No other validation occurs on the client side.
On the server, Salesforce.com:
  1. Loads the original record from the database or initializes the record for an upsert statement.
  2. Loads the new record field values from the request and overwrites the old values. If the request came from a standard UI edit page, Salesforce.com runs system validation to check the record for:
    • Compliance with layout-specific rules
    • Required values at the layout level and field-definition level
    • Valid field formats
    • Maximum field length
    Salesforce.com does not perform system validation in this step when the request comes from other sources, such as an Apex application or a Web Services API call.
  3. Executes all before triggers.
  4. Runs most system validation steps again, such as verifying that all required fields have a non-null value, and runs any user-defined validation rules. The only system validation that Salesforce.com does not run a second time (when the request comes from a standard UI edit page) is the enforcement of layout-specific rules.
  5. Saves the record to the database, but does not commit yet.
  6. Executes all after triggers.
  7. Executes assignment rules.
  8. Executes auto-response rules.
  9. Executes workflow rules.
  10. If there are workflow field updates, updates the record again.
  11. If the record was updated with workflow field updates, fires before and after triggers one more time (and only one more time).
    Note
    The before and after triggers fire one more time only if something needs to be updated. If the fields have already been set to a value, the triggers are not fired again.
  12. Executes escalation rules.
  13. If the record contains a roll-up summary field or is part of a cross-object workflow, performs calculations and updates the roll-up summary field in the parent record.
  14. Commits all DML operations to the database.
  15. Executes post-commit logic, such as sending email.
Note
If you enable the Workflow Rule and Roll-Up Summary Field Evaluations critical update for your organization, Salesforce.com skips steps 7 through 13 during a recursive save. See What is the Spring '09 Workflow Rule and Roll-Up Summary Field Evaluations Update? in the Salesforce.com online help.

Additional Considerations

Please note the following when working with triggers:

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