Question

1) I wish to clarify some doubts on collections.

SampleDBDataContext PersonDB = new SampleDBDataContext("");
Table<Person> p=PersonDB.GetTable<Person>();
IEnumerable<Person> per = PersonDB.GetTable<Person>();
IQueryable<Person> qry = PersonDB.Persons.Select(c => c);

what are the differences between using Table<Person>,IEnumerable<Person>,IQueryable<Person>.Any specific need to choose the particular one?

2) For Adding records Add() method not appears in my IDE,(i.e) PersonDB.Persons.Add().
What is the problem here?

Answer 1

1.

• IEnumerable<> is an interface that
  applies to any collection whose
  members can be enumerated or iterated
  over.

• IQueryable<> is a LINQ interface
  that applies to any collection whose
  members can be lazily queried.
  (queried without materializing the
  result set until its members are
  accessed)

• Table<> is a class that I’ve
  not used before but “represents a
  table for a particular type in the
  underlying database.”

Which one you choose depends on what your needs are, but IEnumerable<> is the most general, so I would use that in my type declarations if it’s sufficient.

2.

To insert a person use InsertOnSubmit():

Person person = new Person() { ... };
PersonDB.Persons.InsertOnSubmit(person);
PersonDB.SubmitChanges();