I have a trigger on the Opportunity that creates records on a custom object called the Opportunity_Revenue__c. It takes the revenue from the Opportunity and spreads it out over the quarters during the length of the deal. It works fine for insert triggers, I need to have the ability to let users re-create based on a changing contract length / deal length. 

So when the record is updated I want to delete all the records in the custom object Opportunity_Revenue__c that are related to the Opportunity and then run the insert code to create the new records for the Opportunity_Revenue__c object. But it is doubling the records because once it deletes the old records it see trigger as an update and an insert.

Can you help or suggest what I might do?

Here is the code:
 

public class OpportunityRevenueTrigger2 {

    
    public static void updateOpportuntityRev(List<Opportunity> trig){
         List<ID> opprtnyId = new List<ID>();
         Decimal totRev;
         Decimal totAllottedRev;
         Decimal mRev;
         
         for(Opportunity opp4: trig){
            if(Opp4.Auto_Generate_Quarterly_Forecast__c == 'Yes'){
                opprtnyId.add(opp4.id);
            }
         List<Opportunity_Revenue__c> deleteOR = [SELECT id
                                                 FROM Opportunity_Revenue__c 
                                                 WHERE Opportunity__c in: opprtnyID];
         
        if(deleteOR.size() != 0){
           Delete deleteOR;
         }
        
        List<Opportunity_Revenue__c> oppr = new List<Opportunity_Revenue__c>();
        for(Opportunity opp : trig){
             
             if(opp.amount > 0 && opp.contract_length_Months__c > 0 
               && opp.Auto_Generate_Quarterly_Forecast__c == 'Yes' ){
                   Date sDate = opp.CloseDate;
                   Integer period = opp.Contract_Length_Months__c.intValue();
                   Integer period2 = period / 3;
                   totRev = opp.Amount;
                   mRev = totRev.divide(period2, 2);
                   for(Integer i = 1; i <= period2; i++) {
                   Opportunity_Revenue__c oppr2 = new Opportunity_Revenue__c();
                   oppr2.Account__c = opp.AccountId;
                   oppr2.Opportunity__c = opp.id;
                   System.debug('i '+ i);
                   oppr2.ProjectedRevenue__c = mRev;
                   oppr2.Month__c = sDate;
                       if(sDate.Month()== 1 || sDate.month()==2 || sDate.month() ==3){
                           oppr2.Quarter__c =  'Quarter 1, '+string.valueOf(sDate.Year());   
                       } else if (sDate.Month()== 4 || sDate.month()== 5 || sDate.month() == 6){
                           oppr2.Quarter__c =  'Quarter 2, '+string.valueOf(sDate.Year());
                       } else if (sDate.Month()== 7 || sDate.month()== 8 || sDate.month() == 9){
                           oppr2.Quarter__c =  'Quarter 3, '+string.valueOf(sDate.Year());
                       } else if (sDate.Month()== 10 || sDate.month()==11 || sDate.month() ==12){
                           oppr2.Quarter__c =  'Quarter 4, '+string.valueOf(sDate.Year());
                       }
                   
                   oppr.add(oppr2);
                   sDate = sDate.addMonths(3);
                   }
                  
        
              }
        }
        insert oppr;

    }
}
}

 

trigger OpportunityRevenueTrigger on Opportunity (after insert, after update) {
  
        
        OpportunityRevenueTrigger2.updateOpportuntityRev(trigger.new);
        
 
  }