I created a dataset (using the Dataset Manager) named ds2.  It is based in the following query:

SELECT code, description, code || ' ' || description AS apparatus FROM apparatus_use

I placed a TCombobox on the form, set it's dataset property to ds2, I set it's datacolumn property to apparatus.  On form create event I added -  Database.Load(ds2);

When I run the app the first item in the query shows in the TCombobox but when I select the dropdown of the TCombobox this value disappears and there isn't any values listed in the dropdown list of the TCombobox.

What am I doing wrong?   FYI, just to check I placed a grid on the form and set it to ds2.  This grid shows all of the records returned by the query

Thanks,
TD

> When I run the app the first item in the query shows in the TCombobox but when I select the dropdown of the TCombobox this value disappears and there isn't any values listed in the dropdown list of the TCombobox.

That's normal, since you haven't defined any items for the drop-down list.

You have to populate the items list yourself, e.g.

   Combobox1.items.clear;
   ds2.first;
   while not ds2.EOF do
   begin
      Combobox1.items.add(ds2.columns['MyColumn'].asString);
      ds2.next;
   end;
   Combobox1.itemindex := 0;

Same in Delphi btw.

Uli

> When I run the app the first item in the query shows in the TCombobox but when I select the dropdown of the TCombobox this value disappears and there isn't any values listed in the dropdown list of the TCombobox.

That's normal, since you haven't defined any items for the drop-down list.

You have to populate the items list yourself, e.g.
>
Same in Delphi btw.

Uli

Ah, I have been spoiled because I use the TDBCombobox in Delphi which does this for you.  Thank you for your help,
TD

I am now getting a new error.  Below is my code, attached is a screen capture of the error message.  Also, if you load the items into a TCombobox "manually" then should you also set the Dataset and DataColumn properties of the TCombobox or just leave them blank?

procedure LoadCombobox1;
begin
  Form1.Combobox1.items.clear;
  Form1.ds2.first;
  while not Form1.ds2.EOF do
  begin
     Form1.ComboBox1.items.add(Form1.ds2.columns['apparatus'].asString);
     Form1.ds2.next;
  end;
  Form1.Combobox1.itemindex := 0;
end;

I run this procedure on formcreate event.

> Ah, I have been spoiled because I use the TDBCombobox in Delphi which does this for you.  Thank you for your help,

I don't think that TDBCombobox does this for you. Maybe you mean
TDBLookupCombobox. That's why I wrote "same in Delphi".

Uli

> I run this procedure on formcreate event.

That cannot work, because the dataset hasn't been loaded yet and maybe
Form1 hasn't be created yet.

Place your code in the ds2.AfterLoad event handler.

Be always aware that eveything runs in an asynchronous way - so make
sure that a dataset has been loaded after doing something with the dataset.

> should you also set the Dataset and DataColumn properties of the
TCombobox or just leave them blank?

If you want the field to be bound to the dataset, then yes. You should
handle a TCombobox just like a TEdit component. You just have a list of
values to choose with the TCombobox.

Uli

Thanks a million Uli, that fixed it !
TD

Uli Becker wrote:

> I run this procedure on formcreate event.

That cannot work, because the dataset hasn't been loaded yet and maybe
Form1 hasn't be created yet.

Place your code in the ds2.AfterLoad event handler.

Be always aware that eveything runs in an asynchronous way - so make
sure that a dataset has been loaded after doing something with the dataset.

> should you also set the Dataset and DataColumn properties of the
TCombobox or just leave them blank?

If you want the field to be bound to the dataset, then yes. You should
handle a TCombobox just like a TEdit component. You just have a list of
values to choose with the TCombobox.

Uli