Hello David,

Is it really true ? The specialist who may do such things can't ask such
question... :-) May be you want to ask: "what I should do after I will
implement IBindingList" ?

You should implement  in your business objects a  set of  XxxxChanged
events, then handle those events and change the underlying dataset.

Hello David,

I can present one "low" that can be interesting for you:

It is impossible to build real world application using "two level data
binding (binding in sence of Windows.Forms Data Binding API)".

Why:

In the real world exists a combobox which values list depends on the other
field value. Therefore you should refresh this combox each time after this
our field was changed. If you are using "buisness logic layer", then you
should rebuild underlying business objects collection. An this is impossible
if you use binding on "SelectedItem" combobox property.

An example:

class Company
{
 CompanyType companyType;
}

class CompanyType
{
   string name;
   public void ToString()
   {
       return name;
   }
}

class CompanyTypes: DictionaryBase
{
  //. CompanyTypes and ther ID
}

class form:Form
{
   // ... somewhere in initialization:
   this.compTypeComboBox.DataSource = new
ArrayList(ResourceManager.CompanyTypes.Values);
   this.compTypeComboBox.DataBindings.Add( "SelectedItem",
company,"CompanyType");
}

Note:
You can't simply construct new CompanyTypes collection based on new query
( SELECT * FROM dbo.CompanyTypes WHERE ...) Of course because you should
maintain Company.CompanyType reference validity. Therefore you should
impplement your own SQL language on your buisness objects. What is not
organic venture for appliactive programming.