global class batch3 implements Database.Batchable<sObject> {
    
    global Database.QueryLocator start(Database.BatchableContext BC) {
 		
        String query = 'SELECT Id,Name,Name__c,MobilePhone,Email,AnnualRevenue,LeadSource FROM Lead';
        return Database.getQueryLocator(query);
      
    }
    global void execute(Database.BatchableContext BC, List<Lead> leadlist) 
    {
        for( Lead a : leadlist)
       {
           for(Lead b: leadlist)
           { 
          		if(a.Name__c == b.Name__c )
                {
                    if(a.MobilePhone== null)
                    {
                        a.MobilePhone=b.MobilePhone;
                    }
                    if(a.Email== null)
                    {
                        a.Email=b.Email;
                    }
                    if(a.AnnualRevenue== null)
                    {
                        a.AnnualRevenue=b.AnnualRevenue;
                    }
                    if(a.LeadSource== null)
                    {
                        a.LeadSource=b.LeadSource;
                    }
                    //delete  b;
                    //[select id from Lead where Name__c='b.Name__c'];
                   	/* Lead[] dlist1 = [SELECT Id, Name FROM Lead WHERE Name__c = 'b.Name__c']; 
						try 
                        {
    						delete dlist1;
						}
                    	catch (DmlException e) 
                        {
    						// Process exception here
						}
					*/
               }
             	
           }
          // update a;
       }
      /* 	system.debug('leadlist a>>>>>'+leadlist);
        system.debug('outside loop>>>>>');
        list<lead> list1=new list<lead>();
      for( Lead a : leadlist)
       {
           for(Lead b: leadlist)
           {
          		if(a.Name__c != b.Name__c )
                {
                   list1.add(a);
                }
               else
                {
                    
                }
           }
           update a;
       }
       // List<Lead> list2 = new List<Lead>(list1);
        */  update leadlist;
        
    }   
     
    global void finish(Database.BatchableContext BC) {
      
  }
}