We know that we can create rollup summary fields for master-detail relationships on salesforce platform. But, there might be a situation where we need rollup summary details for lookup relationship as well. There is no out-of-the-box functionality for this scenario and we have to implement a custom solution for it. Also, this is the most common scenario question asked in salesforce code challenges. We have four types of rollup summary i.e., COUNT, SUM, MIN, MAX. Let's go through an exampl…