function ConvertToDateTime(const AOldValue, AValue : String) : TDateTime;
type
TSeperator = record
  AlphaSection  : String;
  NumSection    : Integer;
  UseCurrentDate: Boolean;
end;

function Parse(const Value : String) : TSeperator;
var
  iCounter  : Integer;
  sNum,
  sValue    : String;

  TAlpha    : set of Char; //'a'..'z';
  TNums     : set of Char; //'0'..'9';
begin
  sNum := '';
  sValue := LowerCase(Value);

  TAlpha := ['a'..'z'];
  TNums  := ['0'..'9'];

  Result.AlphaSection := '';
  Result.NumSection := 0;
  Result.UseCurrentDate := false;

  for iCounter := 1 to Length(sValue) do
  begin
    if sValue[iCounter] in TAlpha then Result.AlphaSection := Result.AlphaSection + sValue[iCounter];
    if sValue[iCounter] in TNums  then sNum := sNum + sValue[iCounter];
    if sValue[iCounter] = '*' then Result.UseCurrentDate := true;
  end;

  if sNum <> '' then
    Result.NumSection := StrToIntDef(sNum, 0);
end;

  var
  sVal        : String;
  iMultiplier : Integer;
  OldDate     : TDateTime;
  Separator   : TSeperator;
begin
  Result := 0;
  iMultiplier := 1;

  OldDate := Now;

  if Trim(AOldValue) <> '' then
    OldDate := StrToDateTimeDef(Trim(AOldValue), Now);

  sVal := Trim(AValue);
  sVal := StringReplace(sVal, 'Ü', 'ü', [rfReplaceAll]);
  sVal := StringReplace(sVal, 'Ş', 'ş', [rfReplaceAll]);
  sVal := StringReplace(sVal, 'İ', 'i', [rfReplaceAll]);
  sVal := LowerCase(sVal);

  sVal := StringReplace(sVal, '.', DateSeparator, [rfReplaceAll]);
  sVal := StringReplace(sVal, ',', DateSeparator, [rfReplaceAll]);
  sVal := StringReplace(sVal, '/', DateSeparator, [rfReplaceAll]);

  if Pos(DateSeparator, sVal) <> 0 then
  begin
    try
      Result := StrToDate(sVal);
      Exit;
    except
    end;
  end;

  if Length(sVal) = 0 then Exit;

  if  (sVal = 'bugün') or
      (sVal = 'bugun') or
      (sVal = 'şimdi') or
      (sVal = 'simdi') or
      (sVal = 'today') or
      (sVal = 'now') then
  begin
    Result := Now;
    Exit;
  end;

  if  (sVal = 'yarın') or
      (sVal = 'yarin') or
      (sVal = 'tomorrow') then
  begin
    Result := Now + 1;
    Exit;
  end;

  if  (sVal = 'dün') or
      (sVal = 'dun') or
      (sVal = 'yesterday') then
  begin
    Result := Now - 1;
    Exit;
  end;

  if sVal[1] = '-' then iMultiplier := -1;

  if (sVal[1] in ['-', '+']) and (Length(sVal) >= 3) then
  begin
    Delete(sVal, 1, 1); // -, +

    Separator := Parse(sVal);

    if Separator.AlphaSection = '' then Separator.AlphaSection := 'g';

    if Separator.AlphaSection = 'g' then // Gün
    begin
      if Separator.UseCurrentDate
      then Result := IncDay(Now, iMultiplier * Separator.NumSection)
      else Result := IncDay(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;

    if Separator.AlphaSection = 'a' then // Ay
    begin
      if Separator.UseCurrentDate
      then Result := IncMonth(Now, iMultiplier * Separator.NumSection)
      else Result := IncMonth(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;

    if Separator.AlphaSection = 'y' then // Yıl
    begin
      if Separator.UseCurrentDate
      then Result := IncYear(Now, iMultiplier * Separator.NumSection)
      else Result := IncYear(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;

    if Separator.AlphaSection = 's' then // Saat
    begin
      if Separator.UseCurrentDate
      then Result := IncHour(Now, iMultiplier * Separator.NumSection)
      else Result := IncHour(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;

    if Separator.AlphaSection = 'dk' then // Dakika
    begin
      if Separator.UseCurrentDate
      then Result := IncMinute(Now, iMultiplier * Separator.NumSection)
      else Result := IncMinute(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;

    if Separator.AlphaSection = 'sn' then // Saniye
    begin
      if Separator.UseCurrentDate
      then Result := IncSecond(Now, iMultiplier * Separator.NumSection)
      else Result := IncSecond(OldDate, iMultiplier * Separator.NumSection);

      Exit;
    end;
  end;

  if (Length(sVal) mod 2) <> 0 then sVal := '0' + sVal;

  if ( Length(sVal) = 6 ) or ( Length(sVal) = 8 ) then // 23052009 , 230509 gibi tarih girişleri
  begin
    Insert( DateSeparator, sVal, 5 );
    Insert( DateSeparator, sVal, 3 );

    TryStrToDate(sVal, Result);
    Exit;
  end;

  raise Exception.Create('Tarih/Saat dönüşümlerinde hata.!');
end;

procedure TForm1.ClientDataSet1SaleDateSetText(Sender: TField;
const Text: String);
begin
  try
    Sender.AsDateTime := ConvertToDateTime(Sender.AsString, Text);
  except
    Sender.AsString := Text;
  end;
end;

uses DateUtils;
VAR
YIL,AY,GUN,SAAT,DAK,SAN,SAL,GUNISIM:STRING;

FUNCTION Tarix (TARIH:TDATETIME):STRING;
var
 myDate : TDateTime;
 myYear, myMonth, myDay,Hour,Minute,Second,Millisecond : Word;
begin
 myDate := TARIH;
//  myDate := IncMonth(myDate);
DecodeDateTime(myDate, myYear, myMonth, myDay,HOUR,MINUTE,SECOND,MILLISECOND);
//  ShowMessage('myDate now = '+DateToStr(myDate));
YIL:=IntToStr(myYear);
AY:=IntToStr(myMonth);
GUN:=IntToStr(myDay);
SAAT:=INTTOSTR(HOUR);
DAK:=INTTOSTR(MINUTE);
SAN:=INTTOSTR(SECOND);
SAL:=INTTOSTR(MILLISECOND);
GUNISIM:=(LongDayNames[dayofweek(MYDate)]);

//---- Ayın Başındaki Sıfırları Düzenle----
IF LENGTH(INTTOSTR(MYMONTH))=1 THEN BEGIN
AY:='0'+INTTOSTR(MYMONTH);
END;
//----Gün onluk Basamak Düzenlemesi---
IF Length(INTTOSTR(MYDAY))=1 THEN BEGIN
GUN:='0'+INTTOSTR(MYDAY);
END;
//-------------Saat Başındaki Sıfırları Düzenle---------
IF Length(INTTOSTR(HOUR))=1 THEN BEGIN
SAAT:='0'+INTTOSTR(HOUR);
END;
//---------Dakika Başındaki Sıfırları Düzenle---------------
IF Length(INTTOSTR(MINUTE))=1 THEN BEGIN
DAK:='0'+INTTOSTR(MINUTE);
END;
End;


// kullanımı
procedure TForm1.Button1Click(Sender: TObject);
begin
TARIX(NOW);
EDIT1.Text:=YIL;
EDIT2.Text:=AY;
EDIT3.Text:=GUN;
EDIT4.Text:=SAAT;
EDIT5.Text:=DAK;
EDIT6.Text:=SAN;
EDIT7.Text:=SAL;
EDIT8.Text:=GUNISIM;
EDIT9.Text:=DATETIMETOSTR(NOW);
end;