Mengkosongkan DBDateTimePicker

Terkadang kita ingin menyimpan data kosong / NULL ke dalam kolom dengan tipe DATE.
Pada saat kita menggunakan komponen DBDateTimePicker, dan sudah terlanjur memilih tanggal, maka ada dua cara untuk membuat kosong datanya
1. Dengan cara mendelete secara manual, klik pada kolom DBDateTimePicker kemudian blok tanggal yang ada, tekan tombol delete.
2. Dengan cara script
Contoh pada event beforepost :
input code berikut ini :

    tbMaster.FieldByName('tukartt_date').AsVariant := null;
    tbMaster.FieldByName('due_date').AsVariant := null;

Semoga membantu.
Thanks

Get Computer Net Name and User Windows

function GetComputerNetName: string;
var
  buffer: array[0..255] of char;
  size: dword;
begin
  size := 256;
  if GetComputerName(buffer, size) then
  Result := buffer
  else
  Result := ''
end;

Function GetUserFromWindows: string;
Var
  UserName : string;
  UserNameLen : Dword;
Begin
  UserNameLen := 255;
  SetLength(userName, UserNameLen) ;
  If GetUserName(PChar(UserName), UserNameLen) Then
  Result := Copy(UserName,1,UserNameLen - 1)
  Else
  Result := 'Unknown';
End;

Get Serial Hard Disk

function GetHardDiskSerial(const DriveLetter: Char): string; 
var 
  NotUsed: DWORD; 
  VolumeFlags: DWORD; 
  VolumeInfo: array[0..MAX_PATH] of Char; 
  VolumeSerialNumber: DWORD; 
begin 
  GetVolumeInformation(PChar(DriveLetter + ':\'), 
  nil, SizeOf(VolumeInfo), @VolumeSerialNumber, NotUsed, 
  VolumeFlags, nil, 0); 
  Result := Format('Label = %s VolSer = %8.8X', 
  [VolumeInfo, VolumeSerialNumber]) 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  ShowMessage(GetHardDiskSerial('c')); 
end;

Clear "Documents" menu

uses
  Shlobj;
...
procedure TForm1.Button1Click(Sender: TObject);
begin
  SHAddToRecentDocs(SHARD_PATH, nil);
end;

Bmp To Jpg and Jpg To Bmp

uses Jpeg;

procedure Bmp2Jpeg(const BmpFileName, JpgFileName: string);
var
 Bmp: TBitmap;
 Jpg: TJPEGImage;
begin
 Bmp := TBitmap.Create;
 Jpg := TJPEGImage.Create;
 try
   Bmp.LoadFromFile(BmpFileName);
   Jpg.Assign(Bmp);
   Jpg.SaveToFile(JpgFileName);
 finally
   Jpg.Free;
   Bmp.Free;
 end;
end;

procedure Jpeg2Bmp(const BmpFileName, JpgFileName: string);
var
 Bmp: TBitmap;
 Jpg: TJPEGImage;
begin
 Bmp := TBitmap.Create;
 Jpg := TJPEGImage.Create;
 try
   Jpg.LoadFromFile(JpgFileName);
   Bmp.Assign(Jpg);
   Bmp.SaveToFile(BmpFileName);
 finally
   Jpg.Free;
   Bmp.Free;
 end;
end;