Hi everyone,
I'm new in salesforce. if you know plz reply 
how to merge duplicate lead with batch apex based on email
Actually i'm unable to merge chatter feed, and fields like name, title, company, fax etc.
plz reply in code becoz if you provide me link and i try, again the same problem occurs. not able to merge fields. i posting second time this question because someone replyed with link and that is not working, and when i asked again i got no reply. 
thanks in advance.


global class LeadBatchAviodDuplicacy implements Database.Batchable<sObject> {

public String queryString;

global Database.QueryLocator start(Database.BatchableContext BC) {
     
  queryString = 'SELECT Id, Name, Email, Phone, Fax, Company FROM Lead ';
    return Database.getQueryLocator(queryString);
}
  global void execute(Database.BatchableContext BC, List<Lead> obj) {

List<Lead> leads = [Select Id, Email, Phone, Fax, Company, Name, (Select Id, WhoId from Tasks), (Select Id, WhoId from Events) from Lead ORDER BY CreatedDate];

Map<String,List<Lead>> leadsMap = new Map<String,List<Lead>>();

for( Lead l : leads ) {
    if( !leadsMap.containsKey( l.Email ) ) {
        leadsMap.put( l.Email, new List<Lead>() );
    }

    leadsMap.get( l.Email ).add( l );
}

List<Event> eventsToUpdate = new List<Event>();
List<Task> tasksToUpdate = new List<Task>();
List<Lead> leadsToDelete = new List<Lead>();


for( String email : leadsMap.keySet() ) {
    List<Lead> leadsToMerge = leadsMap.get( email );
    if( leadsToMerge.size() > 1 ) {
        Lead masterLead = leadsToMerge[0];

        for( Integer i = 1; i < leadsToMerge.size(); i++ ) {
            Lead mergedLead = leadsToMerge[i];
            for( Task t : mergedLead.Tasks ) {
                t.WhoId = masterLead.Id;
                tasksToUpdate.add( t );
            }

            for( Event e : mergedLead.Events ) {
                e.WhoId = masterLead.Id;
                eventsToUpdate.add( e );
            }
            leadsToDelete.add( mergedLead );
        }

    }
}

if( eventsToUpdate.size() > 0 ) update eventsToUpdate;
if( tasksToUpdate.size() > 0 ) update tasksToUpdate;
if( leadsToDelete.size() > 0 ) delete leadsToDelete;
}

global void finish(Database.BatchableContext BC) {

}
}