I'm new to the entity framework and I'm really confused about how savechanges works. There's probably a lot of code in my example which could be improved, but here's the problem I'm having.

The user enters a bunch of picks. I make sure the user hasn't already entered those picks. Then I add the picks to the database.

       var db = new myModel()
       var predictionArray = ticker.Substring(1).Split(','); // Get rid of the initial comma.

        var user = Membership.GetUser();
        var userId = Convert.ToInt32(user.ProviderUserKey);

        // Get the member with all his predictions for today.
        var memberQuery = (from member in db.Members
                         where member.user_id == userId
                         select new
                                    {
                                        member,
                                        predictions = from p in member.Predictions
                                                     where p.start_date == null
                                                     select p

                                    }).First();

        // Load all the company ids.
        foreach (var prediction in memberQuery.predictions)
        {
            prediction.CompanyReference.Load();
        }

 var picks = from prediction in predictionArray
                          let data = prediction.Split(':')
                          let companyTicker = data[0]
                          where !(from i in memberQuery.predictions
                                 select i.Company.ticker).Contains(companyTicker)
                          select new Prediction
                          {
                              Member = memberQuery.member,
                              Company = db.Companies.Where(c => c.ticker == companyTicker).First(),
                              is_up = data[1] == "up",  // This turns up and down into true and false.
                          };


    // Save the records to the database.
    // HERE'S THE PART I DON'T UNDERSTAND.
    // This saves the records, even though I don't have db.AddToPredictions(pick) 
            foreach (var pick in picks)
            {
                    db.SaveChanges();
            }

// This does not save records when the db.SaveChanges outside of a loop of picks.
 db.SaveChanges();
 foreach (var pick in picks)
            {

            }

// This saves records,  but it will insert all the picks exactly once no matter how many picks you have.  
//The fact you're skipping a pick makes no difference in what gets inserted.
            var counter = 1;
            foreach (var pick in picks)
            {
                if (counter == 2)
                {
                    db.SaveChanges();
                }
                counter++;
            }

There's obviously something going on with the context I don't understand. I'm guessing I've somehow loaded my new picks as pending changes, but even if that's true I don't understand I have to loop over them to save changes.

Can someone explain this to me?