The lookup event calculation is one of the lesser used calculation types. It populates a column when a record referenced through a lookup column changes to a given state

This calculation type enables configuration so that when an action is performed on a parent record, a related action can be performed on all child records

The example I’ll go through here will set the course attendee records to a status of event cancelled, when the course event they are linked to gets cancelled

As with all calculated fields the first section contains the calculation type, and the table and column which is populated by the event

The next lookup field section contains the lookup column to the table in which the event will occur. In this example the course attendee table contains a lookup column new_courseevent which references a table of the same name

The next lookup event section includes the value we will populate, and a FetchXml filter defining the state the referenced record must be transitioning into to trigger the calculation event

In this example 100000000 is the picklist value for both the cancelled status on course event records, and the event cancelled status on course attendee record

Viewing the calculation type in effect, here we have a course event about to be cancelled

Upon selection of cancelled and saving, the records in the grid all apply the calculation and have their status set to event cancelled