Trigger for All Rollup Summary calculations on Lookup Relation- Count, Minimum, Maximum, Sum and Average

This trigger will help you to update all the Rollup Summary calculations on Look up RelationShip.

Objects and Fields Information :
Contact (Object) --> Amount__c(Custom Field)
Account (Object) --> Sum__c (Custom Field)
                            --> Avg__c (Custom Field)
                           --> Min__c (Custom Field)
                           --> Max__c (Custom Field)
                           --> Count__c (Custom Field)

Here we are updating all the Account fields based on Contact's Amount__c Field data

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trigger FullRollup on Contact (after insert, after update, after delete, after undelete){ set<Id>Parent_set = new set<id>(); List<Account>AccUpdateList = New List<Account>(); if(trigger.isdelete || trigger.isupdate){ for(Contact con : Trigger.old){ Parent_set.add(con.AccountId); } } if(trigger.isInsert || trigger.isUpdate || trigger.isUndelete){ for(Contact con : Trigger.New){ Parent_set.add(con.AccountId); } } for(AggregateResult aggcon : [Select AccountId, Count(Id)countt, Sum(amount__c)summ, avg(amount__c)avgg, min(amount__c)minn, max(amount__c)maxx From contact Where AccountId IN :Parent_set Group By AccountId]){ Account Acc = New Account(); Acc.Id = (Id)aggcon.get('AccountId'); Acc.Sum__c = (Decimal)aggcon.get('summ'); Acc.Avg__c = (Decimal)aggcon.get('avgg'); Acc.Min__c = (Decimal)aggcon.get('minn'); Acc.Max__c = (Decimal)aggcon.get('maxx'); Acc.Count__c = (Decimal)aggcon.get('countt'); AccUpdateList.add(Acc); } Update AccUpdateList; }