public class TempDeleteOpplgtwithnoOpp {
Public void getalltodeleterecords()
{

    //*Map<ID, Opportunity> Oppmap = new map<id, Opportunity>([SELECT ID, NAME FROM Opportunity LIMIT 10]);
    Set<id> oppidlist = new Set<id>();

    for(Opportunity opp : [SELECT ID FROM Opportunity])
    {
        oppidlist.add(opp.id);
    }

   string OpplgtDelNoOppStringFinal =

    'ID'+','+'Name'+','+'CreatedDate'+','+'LastModifiedDate'+','+'Opportunity_Lgt_Name'+','+' Opportunity_id_txt __c'+'n';


       List<id> opplgttoDelIdSet = new List<ID>();

       for(Opportunity_LGT__C opplgt : [SELECT ID, Name, CreatedDate, LastModifiedDate, Account_Code__c,
                  Opportunity_Lgt_Name__c, Opportunity_id_txt __c FROM Opportunity_LGT__C] )
       {
           IF (!Oppidlist.contains(opplgt.id))
           {
               opplgttoDelIdSet.add(opplgt.id);
               String OpplgtDelNoOppString = opplgt.id +','+opplgt.name+','+opplgt.CreatedDate+','+opplgt.LastModifiedDate+','+opplgt.Opportunity_Lgt_Name__c+','+opplgt.Opportunity_Record_Id__c +'n';
            OpplgtDelNoOppStringFinal = OpplgtDelNoOppStringFinal+ OpplgtDelNoOppString ;
           }
       }

        system.debug('Opplgtlist.size: ' + Oppidlist.size());
        system.debug('opplgttoDelIdSet.size:' + opplgttoDelIdSet.size());

           Messaging.EmailFileAttachment DelOLNoOpp = new Messaging.EmailFileAttachment();
    Blob DelOLNoOppcsvBlob = Blob.valueof(OpplgtDelNoOppStringFinal);
            String DelOLNoOppcsvname = 'DelOLNoOppOL.csv';
            DelOLNoOpp.setFileName(DelOLNoOppcsvname);
            DelOLNoOpp.setBody(DelOLNoOppcsvBlob);


            Messaging.singleEmailMessage ademail = new Messaging.singleEmailMessage();
            List<String> toAddress = new List<String>{'raghavendra.shettigar@inventivHealth.com'};
            ademail.setSubject('OppLightDeleteFiles');
            ademail.setToAddresses(toAddress);
            ademail.setPlainTextBody('Opportunity Light Delete');
            ademail.setFileAttachments( new messaging.emailFileAttachment[]{DelOLNoOpp });
            Messaging.SendEmailResult[] r = Messaging.sendEmail(new Messaging.singleEmailMessage[]{ademail});

set<Id> accIds=new set<Id>();
for(Opportunity opp:[Select AccountId from Opportunity where ID in :setoppIds]){
 accIds.add(opp.AccountId);
}