In this recipe, we will create a conditional validation rule that requires the entry of the reason of why an opportunity has been lost.
The reason lost is a custom field (which we created as
Reason_Lost__c) and is first created using the steps of this recipe.
Creating a custom Reason Lost field on the opportunity:
Scroll down to the Opportunities Custom Fields & Relationships section.
You will find the Step 1. Choose the field type page.
The Step 2. Enter the ...