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Lena ChristyLena Christy 

Trigger to update a field in Account depending on its opportunities

Hi everyone,

I have a question if you could help me it would be awesome.
I have a number custom field in Account field__c, and with a trigger I want all the opportunities' ammount related to the Account get added to this field and be cumulated each time an opp is added to the account.

How can I do it with a trigger please, any idea?

Thanks in advance.

Abhishek Vishwakarma 5Abhishek Vishwakarma 5
Hi Lena,
Here is what you need update this code according to your required amount Field.
// Method called on after Insert of sObject record
  public void onAfterInsert(map<Id, Opportunity> mapNew)

 public void buildCSVOfOpprtunities(map<Id, Opportunity> mapOppId)
    Set<Id> setAccountIds = new Set<Id>();
    Map<Id, String> mapAccountId_OppNamesAsCSV = new Map<Id, String>();
    List<Account> lstAccount = new List<Account>();
    for(Opportunity objOpp: mapOppId.values())
      if(objOpp.AccountId != NULL)
    for(Opportunity objOpp: [SELECT Id, AccountId, Amount_Field 
                 FROM Opportunity 
                 WHERE AccountId in: setAccountIds])
        String strVal = mapAccountId_OppNamesAsCSV.get(objOpp.AccountId);
        mapAccountId_OppNamesAsCSV.put(objOpp.AccountId, strVal + ', ' + objOpp.Amount_Field);  
        mapAccountId_OppNamesAsCSV.put(objOpp.AccountId, objOpp.Amount_Field);  
    for(Id oppId: mapAccountId_OppNamesAsCSV.keySet())
      lstAccount.add(new Account(Id = oppId, field__c  = mapAccountId_OppNamesAsCSV.get(oppId)));    
      update lstAccount;
Select as a Best Answer if this is Helpful.

Amit Chaudhary 8Amit Chaudhary 8
You can create the custum rollup summery field for same.

If you want to do same with trigger only please check below post

Please try below code.
trigger RollUpSummery on Opportunity (after delete, after insert, after update) 
    Set<id> SetAccountId = new Set<id>();
    List<Account> AccountToUpdate = new List<Account>();

        for (Opportunity opp :
    if (Trigger.isUpdate || Trigger.isDelete) 
        for (Opportunity opp : Trigger.old)

    for (Account acc : [select Id, Name,SumOfOppAmount__c, (select id,Amount from Opportunities) from Account where Id IN :SetAccountId]) 
        Integer sumOpp = 0;
        List<Opportunity> lstOpp = acc.Opportunities;
        for(Opportunity opp : lstOpp)
            sumOpp= sumOpp+Integer.valueOf(opp.Amount);
        acc.SumOfOppAmount__c= Decimal.valueOf(sumOpp);

    update AccountToUpdate;

1) One Trigger Per Object
A single Apex Trigger is all you need for one particular object. If you develop multiple Triggers for a single object, you have no way of controlling the order of execution if those Triggers can run in the same contexts

2) Logic-less Triggers
If you write methods in your Triggers, those can’t be exposed for test purposes. You also can’t expose logic to be re-used anywhere else in your org.

3) Context-Specific Handler Methods
Create context-specific handler methods in Trigger handlers

4) Bulkify your Code
Bulkifying Apex code refers to the concept of making sure the code properly handles more than one record at a time.

5) Avoid SOQL Queries or DML statements inside FOR Loops
An individual Apex request gets a maximum of 100 SOQL queries before exceeding that governor limit. So if this trigger is invoked by a batch of more than 100 Account records, the governor limit will throw a runtime exception

6) Using Collections, Streamlining Queries, and Efficient For Loops
It is important to use Apex Collections to efficiently query data and store the data in memory. A combination of using collections and streamlining SOQL queries can substantially help writing efficient Apex code and avoid governor limits

7) Querying Large Data Sets
The total number of records that can be returned by SOQL queries in a request is 50,000. If returning a large set of queries causes you to exceed your heap limit, then a SOQL query for loop must be used instead. It can process multiple batches of records through the use of internal calls to query and queryMore

8) Use @future Appropriately
It is critical to write your Apex code to efficiently handle bulk or many records at a time. This is also true for asynchronous Apex methods (those annotated with the @future keyword). The differences between synchronous and asynchronous Apex can be found

9) Avoid Hardcoding IDs
When deploying Apex code between sandbox and production environments, or installing AppExchange packages, it is essential to avoid hardcoding IDs in the Apex code. By doing so, if the record IDs change between environments, the logic can dynamically identify the proper data to operate against and not fail

Please let us know if this will help you

Amit Chaudhary
Lena ChristyLena Christy

Thanks Abhishek and Amit Chaudhary for your answers, actually it was a large question that I want to adapt on what I need, so exactly I have a field in Account (field__c) already has its value, and each time we have an opportunity for this account, the amount of the opp is substracted from field__c: Account.field__c= Account.field__c - Opportunity.Amount

I hope I explain it well.

Thanks again. 

why are you using a trigger and not a rollup summary field? you could base your formula on the rollup summary field...