Hi,
I'm working on a update trigger, i.e, whenever Account.TID__c (Text field) is changed && Account.AccID__c (unique,ExternalId Text fields) is null, check all account which have Account.AccId__c != null and Account.TID__c !=Account.AccID__C, if it's true copy the Account.TID__c into the Account.AccID__C.   I'm getting the following error

Execution of AfterUpdate caused by: System.QueryException: Non-selective query against large object type (more than 100000 rows). Consider an indexed filter or contact salesforce.com about custom indexing. Even if a field is indexed a filter might still not be selective when: 1. The filter value includes null (for instance binding with a list that contains null) 2. Data skew exists whereby the number of matching rows is very large (for instance, filtering for a particular foreign key value that occurs many times): Class.UpdateAccIDController.updateAccID:

Any one can help me please ?.

Here is my code

trigger UpdateAccID  on Account (after update) {
if ( Trigger.isUpdate ) {
      UpdateAccIDController.updateAccID(trigger.oldMap, trigger.newMap);
  }
 
}


public class UpdateAccIDController{

public static void updateAccID(Map<ID, Account> oldAccts, Map<ID, Account> newAccts){

Map<ID, Account> accounts = new Map<ID, Account>();

  for(Account acc: newAccts.values()){
    Account oldAcc = oldAccts.get(acct.Id);
      if (acc.TID__c!= oldAcc.TID__c && acc.AccId__c == null){

        for(Account accList:[select Id,AccID__c FROM Account WHERE AccID__c !=null]){
   
              if( acc.TID__c != accList.AccID__c){
                   acc.AccID__c = acc.TID__c;
                 }
       
        }

        
      }
    update acc;
          
    }

  }
}

Thank a lot .

Regards,

SK