In this task you will add the ability to set a range on your table using the active index. For more information on ranges, see Index Scopes (Ranges) or reference your Delphi documentation.

Add Range GroupBox

Object Inspector:

Name - grpbxRange

Caption - Range

 

Figure 10 - Browser with the New Range GroupBox

 

Add RangeTop and RangeBottom Edit Boxes

Object Inspector:

Caption - Top

 

Object Inspector:

Name - ebRangeTop

Text - " (empty string)

 

Object Inspector:

Caption - Bottom

 

Object Inspector:

Name - ebRangeBottom

Text - " (empty string)

 

Object Inspector:

Name - btnSetRange

Caption - Set

 

 

procedure TForm1.btnSetRangeClick(Sender: TObject);
var
 def: TIndexDef;
begin
 {* make sure there is an active index *}
 with cbActiveIndex do
 begin
   if Items[ItemIndex] = 'Natural Order' then
   begin
     Application.MessageBox( 'No Active Index', 'Error', 0 );
     exit;
   end;
 end;
 
 if btnSetRange.Caption = 'Set' then
 begin
   {* set the range *}
   with tblCustomer do
   begin
     try
       SetRangeStart;
       def := IndexDefs.
       Find(cbActiveIndex.Items[cbActiveIndex.ItemIndex]);
       FieldByName(def.fields).asstring := ebRangeTop.Text;
       SetRangeEnd;
       FieldByName(def.fields).asstring := ebRangeBottom.Text;
       ApplyRange;
     except
       on E: Exception do
       begin
         Application.MessageBox( PChar(E.message), 'Error', 0 );
         exit;
       end;
     end;

 
     btnSetRange.Caption := 'Clear';
   end;
 end {* if setting range*}
 else
 begin
   {* clear the range *}
   tblCustomer.CancelRange;
   btnSetRange.Caption := 'Set';
 end;
end;

 

Note For more information about SetRangeStart, SetRangeEnd, and ApplyRange reference your Delphi documentation.

 

Save and Run