c# - Filtering a collection of objects by ID -

teaching myself c# , problem have class creates person objects , adds them list (mypersonlist). have partygroup class takes personlist 1 of properties. issue mypersonlist contains whole results set @ moment each time creates new partygroup adds values in mypersonlist. there way tell add values in mypersonlist person.partygroupid matches current partygroup groupid dealing with. hope makes sense. thanks.

//person

using (asedatareader reader = commandperson.executereader())          {             while (reader.read())             {                 person person = new person();                 person.personid = convert.toint32(reader["person_id"]);                 person.partygroupid = convert.toint32(reader["party_group_id"]);                 person.fullname = reader["full_name"].tostring();                  mypersonlist.add(person);             }         } 

//partygroup

using (asedatareader reader = commandpartygroup.executereader())          {             while (reader.read())             {                 int groupid = convert.toint32(reader["party_group_id"]);                  if (mypartygrouplist.where(partygroup => partygroup.partygroupid == groupid).any() == false)                  {                     partygroup partygroup = new partygroup()                     {                         partygroupid = groupid,                         partygroupname = reader["party_group_name"].tostring(),                         personlist = mypersonlist//where personlist objects contain groupid???                       };                      mypartygrouplist.add(partygroup);                  }              }          } 

if understand problem correctly, need:

personlist = mypersonlist.where(p => p.partygroupid == groupid).tolist();