Hi Guys,

I'm a newbie with Apex coding and I'm trying to summarize the value of List and then have the output to a field in the Account.

My Trigger is on Account object and I'm trying to query all the Contacts and then Sum a number field from contact object. (Like Roll up summary field)

List<Contact> conList = [SELECT NumFieldFromContact__c FROM CONTACT WHERE ID IN: <AccountID>];

Account A has 3 Contacts, and the NumFieldFromContact__c contains 10 value. So when my trigger run, the field under Account Object should be updated with the 30 Value.

Here's what I'm testing in Developer Console.

String accID = '0019000001EnVzf';
List<Contact> conList = [SELECT NumFieldFromContact__c FROM Contact WHERE contact.Account.id = :accID];

Integer i=0;
Double x;
Double y;

Do {
    x = conList[i].Formula_Number_Field__c;
    y = x + x;
    i++;
    
} WHILE (i<conList.size());
    
System.debug(y);

Just experimenting on how things works. Can anyone please give me a correct syntax and Explanation of the Line? :)