Sample Batch Apex Code
public class UpdateContactAddresses implements
Database.Batchable<sObject>, Database.Stateful {
// instance member to retain state across transactions
public Integer recordsProcessed = 0;
public Database.QueryLocator start(Database.BatchableContext bc) {
return Database.getQueryLocator(
'SELECT ID, BillingStreet, BillingCity, BillingState, ' +
'BillingPostalCode, (SELECT ID, MailingStreet, MailingCity, ' +
'MailingState, MailingPostalCode FROM Contacts) FROM Account ' +
'Where BillingCountry = \'USA\''
);
}
public void execute(Database.BatchableContext bc, List<Account> scope){
// process each batch of records
List<Contact> contacts = new List<Contact>();
for (Account account : scope) {
for (Contact contact : account.contacts) {
contact.MailingStreet = account.BillingStreet;
contact.MailingCity = account.BillingCity;
contact.MailingState = account.BillingState;
contact.MailingPostalCode = account.BillingPostalCode;
// add contact to list to be updated
contacts.add(contact);
// increment the instance member counter
recordsProcessed = recordsProcessed + 1;
}
}
update contacts;
}
public void finish(Database.BatchableContext bc){
System.debug(recordsProcessed + ' records processed. Shazam!');
AsyncApexJob job = [SELECT Id, Status, NumberOfErrors,
JobItemsProcessed,
TotalJobItems, CreatedBy.Email
FROM AsyncApexJob
WHERE Id = :bc.getJobId()];
// call some utility to send email
EmailUtils.sendMessage(job, recordsProcessed);
}
}