Hi,

Batch Apex is exposed as an interface that must be implemented by the developer. Batch jobs can be programmatically invoked at runtime using Apex.

Need of Batch Apex: - As you all might know about the salesforce governor limits on its data. When you want to fetch thousands of records or fire DML on thousands of rows on objects it is very complex in salesforce and it does not allow you to operate on more than certain number of records which satisfies the Governor limits.

But for medium to large enterprises, it is essential to manage thousands of records every day. Adding/editing/deleting them when needed.

Salesforce has come up with a powerful concept called Batch Apex. Batch Apex allows you to handle more number of records and manipulate them by using a specific syntax.

We have to create an global apex class which extends Database.Batchable Interface because of which the salesforce compiler will know, this class incorporates batch jobs. Below is a sample class which is designed to delete all the records of Account object (Lets say your organization contains more than 50 thousand records and you want to mass delete all of them).

Examples:-

global class deleteAccounts implements Database.Batchable

{

global final String Query;

global deleteAccounts(String q)

{

Query=q;

}

global Database.QueryLocator start(Database.BatchableContext BC)

{

return Database.getQueryLocator(query);

}

global void execute(Database.BatchableContext BC,List scope)

{

List <Account> lstAccount = new list<Account>();

for(Sobject s : scope)

{

 Account a = (Account)s;

lstAccount.add(a);

}

Delete lstAccount;

}

global void finish(Database.BatchableContext BC)

{

                //Send an email to the User after your batch completes

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

String[] toAddresses = new String[] {‘sforce2009@gmail.com’};

mail.setToAddresses(toAddresses);

mail.setSubject('Apex Batch Job is done‘);

mail.setPlainTextBody('The batch Apex job processed ');

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

}

}

//This is how the batch class is called.

id batchinstanceid = database.executeBatch(new deleteAccounts(‘select Id from Account’))

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