Update all Records

public class UpdateBulkAccountsEmailBatch implements Database.Batchable<sObject>, Database.Stateful {
    
    private Integer emailCounter;
    private static final String EMAIL_COUNTER_SETTING = 'Email_Counter';
    private Integer recordsProcessed = 0;
    private final Integer BATCH_SIZE = 10000;

    public UpdateBulkAccountsEmailBatch() {
        this.emailCounter = getLastEmailCounter();
    }

    public Database.QueryLocator start(Database.BatchableContext bc) {
        return Database.getQueryLocator([
            SELECT Id, Name, CustomEmail__c 
            FROM Account 
            WHERE Name LIKE 'Bulk Account%'
            ORDER BY Id
        ]);
    }
    
    public void execute(Database.BatchableContext bc, List<Account> scope) {
        List<Account> accountsToUpdate = new List<Account>();
        
        for (Account acc : scope) {
            acc.CustomEmail__c = 'tesths' + emailCounter + '@gmail.com';
            accountsToUpdate.add(acc);
            emailCounter++;
            recordsProcessed++;
        }
        
        if (!accountsToUpdate.isEmpty()) {
            Database.SaveResult[] results = Database.update(accountsToUpdate, false);
            // Process errors if any
            for (Database.SaveResult result : results) {
                if (!result.isSuccess()) {
                    System.debug('Error updating Account: ' + result.getErrors());
                }
            }
        }
    }
    
    public void finish(Database.BatchableContext bc) {
        saveLastEmailCounter(emailCounter);
        System.debug('Batch job completed. Records processed: ' + recordsProcessed + '. Last email counter: ' + (emailCounter - 1));
        
        // Check if there are more records to process
        Integer remainingRecords = [SELECT COUNT() FROM Account WHERE Name LIKE 'Bulk Account%' AND CustomEmail__c = null];
        if (remainingRecords > 0) {
            // Chain the next batch job
            UpdateBulkAccountsEmailBatch nextBatch = new UpdateBulkAccountsEmailBatch();
            Database.executeBatch(nextBatch, BATCH_SIZE);
        }
    }
    
    private Integer getLastEmailCounter() {
        Email_Counter__c counterSetting = Email_Counter__c.getOrgDefaults();
        
        if (counterSetting.Counter__c != null) {
            return Integer.valueOf(counterSetting.Counter__c);
        } else {
            Email_Counter__c newSetting = new Email_Counter__c(
                SetupOwnerId = UserInfo.getOrganizationId(),
                Counter__c = 50020
            );
            upsert newSetting;
            return 50020;
        }
    }
    
    private void saveLastEmailCounter(Integer counter) {
        Email_Counter__c setting = Email_Counter__c.getOrgDefaults();
        setting.Counter__c = counter;
        upsert setting;
    }
}