how to prevent field update multiple times in workflow

Question

I have a picklist and date fields on custom object object__c

• date__c - field
• picklist__c - field

I am updating date__c field with date when picklist__c is updated from workflow on below criteria.

AND(
    ISNEW(),
    NOT(ISPICKVAL(picklist__c,''))
)
|| ISCHANGED(Picklist__c).

In this criteria, when ever the picklist is changed, then date is updated.

I am trying to write logic, such that date field populated when the picklist is updated and cannot be changed once it is populated. Can someone help me write the logic.

Answer 1

If I understand correctly, you want to populate date__c field only when picklist__c value is set for the first time. This should do it:

AND(
 OR(
  ISCHANGED(Picklist__c),
  ISNEW()
 ),
 NOT(ISBLANK(TEXT(picklist__c))),
 ISBLANK(date__c)
)