[SalesForce] Validation Rule to auto populate Date field when a picklist value is selected

I have made a validation rule below to auto populate a date field to today if picklist value is selected, but this seems to be not working:

AND( Offer_Stage_Date__c > today() ) ((OR(ISPICKVAL (Offer_Stage__c, "placed"))

Can you please what am i doing wrong?

Best Answer

Validation Rules don't populate anything, they block database operations. You want to use a Workflow with a Field Update.

Create a new Workflow Rule:

Create > Workflow & Approvals > Workflow Rules > New Rule

Select your object. Then you will need to give it a Name and define Evaluation Criteria and Rule Criteria:

screenshot

Then you need to add a Field Update:

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Now give it a Name, Unique Name, and select the field you wish to update.

When prompted to specify a value, use a formula that evaluates to TODAY():

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