Testing multiple TComboBox values at once

I'm a noob at Delphi but please help.

I have 7 TComboBoxes on a form. Their values are assigned to them using a SQL query from the same table called Numbers.

procedure TForm3.Button4Click(Sender: TObject);
begin

Q2.Close;
Q2.SQL.Clear;
Q2.SQL.Add ('Select num');
Q2.SQL.Add ('FROM numbers.dbf');
Q2.RequestLive := true;
Q2.Open;
cb1.Items.Add(q2.FieldByName('num').value);
cb1.Text:= '? ? ?';
cb2.Items.Add(q2.FieldByName('num').value);
cb2.Text:= '? ? ?';
...
...
...
end;

Where cb1, cb2.... are TComboBoxes.

I'm trying to get them to test their values (all values are text) against one another when you 开发者_Python百科click on them. Specifically, if you select cb1 = 1 from the dropdown, then if you select cb2 = 1 ...etc and you assign the same number, it should give you an error message

MessageDlg('Check Values: CB 1 and CB 2: Same Values Entered.',mtError, mbOKCancel, 0);

Which method would you recommend I use, I've been battling for two days now.

Thanks in advance!

Create a new form with seven combo boxes (with Style := csDropDownList). Then, create a

var
  combos: array[1..7] of TComboBox;

and initiate it:

procedure TForm1.FormCreate(Sender: TObject);
begin
  combos[1] := ComboBox1;
  combos[2] := ComboBox2;
  combos[3] := ComboBox3;
  combos[4] := ComboBox4;
  combos[5] := ComboBox5;
  combos[6] := ComboBox6;
  combos[7] := ComboBox7;
end;

Then you can just do

procedure TForm1.VerifyUniqueness(Sender: TObject);
begin
  if LongBool(TComboBox(Sender).Perform(CB_GETDROPPEDSTATE, 0, 0)) then
    Exit;
  for i := low(combos) to high(combos) do
    if (Sender <> combos[i]) and SameStr(TComboBox(Sender).Text, combos[i].Text) then
      raise Exception.CreateFmt('The fields %s and %s have the same value.', [TComboBox(Sender).Name, combos[i].Name]);
end;

and assign VerifyUniqueness to the OnChange event of each combo box. In addition, you need

procedure TForm1.ComboBoxesKeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if Key = VK_RETURN then VerifyUniquness(Sender);
end;

Validating each time a Combo Box's value changes does lead to a small inconvenience. If you want to swap the values of two Combo Boxes, you have to do so in a roundabout way.

• Set the first to a temporary third value.
• Set the second to the original first value.
• Set the first to the original second value.

The following code provides a means to validate all Combo Boxes at any point in time. E.g. When the user clicks the Ok button. Of course, you could still call the method each time a value changes.

The code also uses an array of combo boxes as with Andreas Rejbrand's answer, so I'll not repeat that portion of the code.

procedure ValidateComboBoxes;
var
  LCombValues: TStrings;
  I: Integer;
  LDuplicateIndex: Integer;
begin
  LComboValues := TStringList.Create;
  try
    for I := Low(FCombos) to High(FCombos) do
    begin
      LDuplicateIndex := LComboValues.IndexOf(FCombos[I].Text);
      if (LDuplicateIndex >= 0) then
      begin
        raise Exception.Create('The value: ['+FCombos[I].Text+
          '] has been duplicated in the following Combo Boxes: ['+FCombos[I].Name+
          '] and ['+TComboBox(LComboValues.Objects[LDuplicateIndex]).Name+']');
      end;
      LComboValues.AddObject(FCombos[I].Text, FCombos[I]);
    end;
  finally
    LComboValues.Destroy;
  end;
end;