Order of Execution in Salesforce

 Order of Execution in Salesforce :

1. First things first, the original record is loaded from the database or initialized for an upsert statement.
2. The new field values are loaded by overwriting the old values and Salesforce runs system validation (If the request came from a standard UI edit page) to check the record for:
   • Layout-specific rules such as Required values at the layout level and field-definition level
   • Valid field formats or Maximum field length
3. Record-triggered flows are executed that are configured to run before the record is saved.
4. Next, all Apex Before Triggers are executed.
5. Salesforce runs system validation steps again, such as verifying that all required fields have a non-null value, and then runs any custom validation rules.
6. Duplicate rules are executed after custom validation rules.
   • Note: If the duplicate rule identifies the record as a duplicate and uses the block action, the record is not saved and no further steps, such as  triggers and after workflow rules, are taken.
7. The record  is saved to the database, but doesn’t commit yet.
8. All after apex triggers are executed.
9. Next, assignment rules are run.
10. Followed by the execution of auto-response rules.
11. Salesforce runs Workflow rules and if there are workflow field updates:
    • Updates the record again.
    • Runs system validations again. Custom validation rules, flows, duplicate rules, processes, and escalation rules are not run again.
    • Executes before update triggers and after update triggers, regardless of the record operation (insert or update), one more time (and only one more time)
12. Escalation rules are executed next.
13. Salesforce  then executes the following Flow automations, but not in a guaranteed order.
    • Processes
    • Flows launched by processes
    • Flows launched by workflow rules (flow trigger workflow actions pilot)

    When a process or flow executes a DML operation, the affected record goes through the save procedure.

14. Followed by, record-triggered flows that are configured to run after the record is saved.
15. Executes entitlement rules.
16. 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. Parent record goes through save procedure.
17. If the parent record is updated, and a grandparent 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 grandparent record. Grandparent record goes through save procedure.
18. Salesforce then executes Criteria Based Sharing evaluation.
19. Lastly, Commits are made to the database for all DML operations.
20. After the changes are committed to the database, Salesforce executes post-commit logic such as sending email and executing enqueued asynchronous Apex jobs, including queueable jobs and future methods.

Questions :

Ques : Do workflow rules run before process builder? 

Ans : Workflow Rules are evaluated after Process Builder execution with no DML Operations.If the record was updated with workflow field updates, fires before update triggers and after update triggers one more time (and only one more time), in addition to standard validations.

Ques : If field gets update from workflow and we need to validate this, will validations work here ? If not then how ? If yes then how?

Ans : No. Because according to order of execution workflow comes after validation. So in this we can use Trigger to validate this, we can use "AddError" method in After Trigger scenario.