Saving query results locally in C#

Using SessionState is the solution.

Let us assume that you have a Car object which some basic properties, along with a CarDetail object property, something like as follows:

public class Car
{
  public string Make {get;set;}
  public string Model {get;set;}
  //Other basic properties
  public CarDetail {get;set;}
}

The CarDetail class may have some detail properties as follows:

public class Car
{
  public int Year {get;set;}
  public Coler coler {get;set;}
  //Other detail properties...
}

And, the CarDetail may have another objects as it's property.

Let's call this an object graph, where the Car object contains other object (CarDetail) which may contain other object(s) as property.

So, what you have to do is, when your page is loaded first, you load all basic and detailed information for the requested Car from the database and populate the data in the Car object graph. Then, you store the Car object in the Session. For later page request, you serve the Car object data from the Session.

Here is a sample method that does this:

protected Car GetCar(int carId)
{
    Car car = null;
    if(Session["Car"] == null)
    {
        car = GetCar(carId); //Populate the Car object graph from database
        Session["Car"] =  car; //Store in the session
    }
    else
    {
        car = Session["Car"] as Car; //Get the Car object from Session
    }
    return car;
}

Hope, this helps