Roll-Up Summary Fields
Roll-up summary fields calculate values from a set of related records, such as those in a related list. You can create roll-up summary fields that automatically display a value on a master record based on the values of records in a detail record. These detail records must be directly related to the master through a master-detail relationship. You can perform different types of calculations with roll-up summary fields. You can count the number of detail records related to a master record, or calculate the sum, minimum value, or maximum value of a field in the detail records. Since roll-up summary fields are based on master-detail relationships, it’s useful to review object relationships before creating a roll-up summary field. Master-Detail Relationships Master-detail relationships closely link objects together so that the master record controls specific behaviours of the detail and sub-detail record. You define a roll-up summary field on the object that is on the ...