ERROR: must implement the method: System.Iterable<SObject> Database.Batchable<>.start(Database.BatchableContext)

Question

global Class Batchsample implements Database.Batchable<Attendance__c>{

    global Database.QueryLocator start(Database.BatchableContext BC){
        String Query = 'select id,Login_Date_c,Leave_Type__c from Attendance__c where Login_Date__c = LAST_N_DAYS:35 AND Leave_Type__c not in (SL,EL,AL,Half Day)';

        return Database.getQueryLocator(Query);
    }


    global void execute(Database.BatchableContext BC,list<Attendance__c> scope){

        Integer size = scope.size();
         for(Integer i=0; i< size; i++)
         {
            del.add(i);
         }
            delete del;
    }


global void finish(Database.BatchableContext BC){
    }
}

Answer 1

It's a weird behavior with the compiler. Change it to Database.Batchable<sObject> instead.

Notes:

• You don't need to copy the list before deleting it.
• Use an inline query.
• Don't query fields you don't need.

---

global Class Batchsample implements Database.Batchable<sObject>{
    
    global Database.QueryLocator start(Database.BatchableContext BC){
        return Database.getQueryLocator([
            select id from Attendance__c 
            where Login_Date__c = LAST_N_DAYS:35 AND 
                Leave_Type__c not in ('SL','EL','AL','Half Day')
        ]);
    }
    global void execute(Database.BatchableContext BC,list<Attendance__c> scope){
        delete scope;
    }
    global void finish(Database.BatchableContext BC){
    }
}