Using batch class to update record’s field and send email notification in finish method on custom Object in Salesforce | batch class to update records on custom object in salesforce

   global class batch_scoreCardEmailUpdate Implements DATABASE.Batchable<sobject> {

    global DATABASE.QueryLocator START(DATABASE.BatchableContext BC){

        string query = 'Select Id, Name, Email__c, City__c, Phone_No__c From scoreCard__c Where Name !=null';

        RETURN DATABASE.getQueryLocator(query);        

    }

    global void EXECUTE(DATABASE.BatchableContext BC, List<scoreCard__c> scope){

         List<scoreCard__c> scoreUpate = NEW List<scoreCard__c>(); 

        FOR(scoreCard__c scoreObj: scope){

            scoreObj.Email__c = 'w3webmart@gmail.com';

            scoreObj.City__c = 'Delhi';

            scoreUpate.add(scoreObj);

        } 

        system.debug('scoreUpate@@ ' + scoreUpate);

        UPDATE scoreUpate;        

    }

    global void finish(DATABASE.BatchableContext BC){

       AsyncApexJob a = [SELECT Id, STATUS, NumberOfErrors, JobItemsProcessed,

          TotalJobItems, CreatedBy.Email

          FROM AsyncApexJob WHERE Id =

          :BC.getJobId()];

       Messaging.SingleEmailMessage mail = NEW Messaging.SingleEmailMessage();

       String[] toAddresses = NEW String[] {a.CreatedBy.Email};

       mail.setToAddresses(toAddresses);

       mail.setSubject('Apex Sharing Recalculation schedule email update' + a.Status);

       mail.setPlainTextBody

       ('The batch Apex job processed scoreCard update ' + a.TotalJobItems +

       ' batches with '+ a.NumberOfErrors + ' failures.');

       Messaging.sendEmail(NEW Messaging.SingleEmailMessage[] { mail });    

    }

}

  batch_scoreCardEmailUpdate scoreCard_batch = NEW batch_scoreCardEmailUpdate();

  DATABASE.executeBatch(scoreCard_batch,10);