A Small ADO.NET Library with Some ORM Capabilities

using System;
using System.Collections;
using System.Collections.Generic;
using Sqless;

[Table("customers", "dbo")]
public class Customer
{
    private int id = 0;
    private string name = string.Empty;
    
    public Customer()
    {}
    
    [Field("cust_id", FieldFlags.Read | FieldFlags.Key | FieldFlags.AutoGen)]
    public int ID
    {
        get { return id; }
        set { id = value; }
    }
    
    [Field("cust_name")]
    public string Name
    {
        get { return name; }
        set { name = value; }
    }
    
    public List<Purchase> GetPurchases()
    {
        Query query = new Query().Eq("cust_id", id).Order("pur_date", true);
        List<Purchase> list = Program.database.Select<Purchase>(query);
        return list;
    }
    
    public virtual Purchase Buy(Product product, int quantity)
    {
        Purchase pur = new Purchase();
        pur.SetCustomer(this);
        pur.SetProduct(product);
        pur.Quantity = quantity;
        pur.PurchaseDate = DateTime.Now;
        Program.database.Insert(pur);
        return pur;
    }
    
    public override string ToString()
    {
        return "<Customer id=" + id + ", name=" + name + ">";
    }
}