請參見如下 strResult 即可以得到你要的結果
System.Globalization.DateTimeFormatInfo formatInfo = new System.Globalization.DateTimeFormatInfo();
formatInfo.AMDesignator = "AM";
formatInfo.PMDesignator = "PM";
formatInfo.ShortDatePattern = "dd/MM/yyyy tt";
DateTime end = DateTime.Parse("2003-1-20 16:40");
string strResult = end.ToString(formatInfo.ShortDatePattern,formatInfo);
System.Globalization.DateTimeFormatInfo formatInfo = new System.Globalization.DateTimeFormatInfo();
formatInfo.AMDesignator = "AM";
formatInfo.PMDesignator = "PM";
formatInfo.ShortDatePattern = "dd/MM/yyyy tt";
DateTime end = DateTime.Parse("2003-1-20 16:40");
string strResult = end.ToString(formatInfo.ShortDatePattern,formatInfo);
Response.Write(dt.ToString("yyyy-mm-dd hh:mm,tt"));