59、salesforce实现数据的批量处理

批处理，往自己的邮箱发一封邮件，批处理采用异步的处理方式处理数据，最多可以处理5000万条数据

global with sharing class MerchandiseBatch implements Database.Batchable<sObject>,Database.Stateful{
    Integer queryCount = 0;
    String myEmailAddress = ‘[email protected]‘;
    global Database.QueryLocator start(database.BatchableContext bc){
        String query  = ‘select Name from Merchandise__c‘;
        return Database.getQueryLocator(query);
    }

    global void execute (Database.BatchableContext bc,List<Merchandise__c> merchandiseList){
        for(Merchandise__c merchandise : merchandiseList){
            Decimal price = merchandise.Price__c;
            price += 1;
            queryCount +=1;
        }
        upsert merchandiseList;
    }

    global void finish(Database.BatchableContext bc){
        System.debug(‘query count: ‘+ queryCount);
        Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
        email.setToAddresses(new String[]{myEmailAddress});
        email.setSubject(‘show count‘);//set subject
        email.setHtmlBody(‘query Count‘ + queryCount);
        Messaging.sendEmail(new Messaging.SingleEmailMessage[]{email});
    }
}

MerchandiseBatch merchandise = new MerchandiseBatch();
Id batchId = Database.executeBatch(merchandise);