Design Question (Class vs Structs)

[student_rhr]

Hi Everyone, I have a "one to many" sort of situation. I am using a Key to get subset data. I started out using a class like this:

public class Contract
{
    public int ContractID {get;set;}
    public int CustomerID {get;set;}
    public string CustomerName {get;set;}
    public string Organization {get;set;}
    public int TermsID {get;}
}
//Then data mapper
public class ContractDataMapper
{
    public static List<Contract> GetContractData(int contractID)
    {
        List<Contract> returnValue = new List<Contract>();
        ... /*data retrieval logic*/
        while(reader.Read())
        {
            Contract contract = new Contract();
            contract.CustomerID = Convert.ToInt32(reader["CustomerID"]);
            contract.CustomerName = reader["CustomerName"].ToString();
            ...
            if(!returnValue.Contains(contract))
                returnValue.Add(contract);
        }
        reader.Close();
        command.Dispose();
        return returnValue();
    }
}

But I soon realized that this is bad because I had to check to see if this ContractID has any TermsID associated with it and the way it currently is I would have to do something like:

if(ContractDataMapper.GetContractData(1234)[0].TermsID > 0)
    // Do something

Ideally I should have one class Contract and have other properties in a subclass. Now my question is ... do you think it would be better to have a struct or a subclass or something else?

// Something like this
Contract contract = new Contract(1234);
List<SubsetData> subset = contract.SubsetData;

I would appreciate your help.

[PIEBALDconsult]

Probably a class.