public class ProductSale{
 public long ID {get; set;}
 public long ProductID {get; set;}
 public DateTime SaleDate {get; set;}
 ...
}

public class Product{
  public long ID {get; set;}
  public string Description {get; set;}
  public long ProductCategoryID {get; set;}
...
}

public class ProductCategory{
 public long ID {get; set;}
public string Description {get; set;}
}

public class UserPrefrenceCategory{
  public long ID {get; set;}
  public string Description{get; set;}
}
public class UserPrefrenceCategoryProduct{
  public long UserPrefrenceCategoryID {get; set;}
  public long ProductID {get; set;}
}