Background: It is often times essential to identify a primary contact or specific "role" within an account. This may be for support or sales reasons. You may want to identify the primary contact's email address or other key piece of contact information and have it accessible to workflow, other business processes, or simply to just display the information/primary contact at the account level. Let's say you have a picklist field or checkbox field that denotes a contact as being the primary contact on an account. How do you populate a contact lookup on the account page that identifies who this contact is?
Create what we have coined a "Lookup Rollup" in Salesforce.
1) Create a contact lookup field on the account object.
2) Create a text rollup that rolls up the contact's id.
3) Create a filter that limits the rollup to 1 record. HINT: Add "1" to the limit field to choose only one contact as primary.
4) Optional: If you can have multiple primary contacts on your record, using the sort order functionality to change which contact is picked first. You might use created date, last modified date for example.
4) Add a criteria that establishes how to identify the primary contact. This is where you plug in how to tell Rollup Helper and Salesforce that your contact is a primary contact. This is different for every company.
5) Run your rollup.
1) Add formula fields to display primary contact information on the account page like primary contact's phone number or title.
2) Use workflow or process builder to identify when a prospect becomes a customer, and send an email to the primary contact thanking them for their order or introducing them to someone.
3) If you use Opportunity Contact Roles and have a role of "Decision Maker" or "Primary", use that as criteria to automatically mark a contact as primary at the contact level. Thus, all these rollups fire from the Opportunity Contact Roles related list and you minimize data entry for your users.