将格式从dd/mm/yyy更改为yyyy-mm-dd HH:mm:ss

场景：我有一个格式为"yyyy-mm-dd HH:mm:ss"的输入字符串。我在将其转换为日期时间格式时遇到问题。我需要这个日期时间输出到数据库列，并返回一个与我传递的日期时间相对应的注释。HEre是我的代码：我试图用Datetime.ParseExact转换字符串，但它返回另一种格式。

我不知道哪里出了问题。请帮助

这是我的代码：[HttpPost]

    public string getdailynote(string selectedDate)
        { 
        tablenote Dnote= new tablenote;
        DateTime selectedDate1 = DateTime.ParseExact(selectedDate,
                                           "yyyy-mm-dd HH:mm:ss",
                 CultureInfo.InvariantCulture);
        Dnote.RealDate = selectedDate1;
        string daily;
        daily = _scheduler.GetDailyNote(selectedDate1);
        return daily;
    }

view.cshtml:

function getdailynotes() {
           debugger;
           var calendar = $("#SchedulerCalendar").data("kendoCalendar");
           var view = calendar.value();
           var kendodate = dateFormat(view, 'yyyy-mm-dd HH:mm:ss');
           $.ajax({
               type: "POST",
               url: window.location.pathname + "Scheduler/getdailynote",
               data: { selectedDate: kendodate }
           })
        .success(function (result) {
               if (result != null) {
                document.getElementById('dailynotes').value = result;
            }
        });
   }

更新：服务.cs_schedulefile：

public string GetDailyNote(DateTime selectedDate)
        {
            string returndaynote;
            returndaynote = dbContext.GetDailyNote(selectedDate).SingleOrDefault();
            return returndaynote;
        }
from autogenerated context.cs
 public virtual ObjectResult<string> GetDailyNote(Nullable<System.DateTime> realDate)
        {
            var realDateParameter = realDate.HasValue ?
                new ObjectParameter("RealDate", realDate) :
                new ObjectParameter("RealDate", typeof(System.DateTime));
            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<string>("GetDailyNote", realDateParameter);
        }

DateTime selectedDate1 = DateTime.ParseExact(
    selectedDate,
    "yyyy-MM-dd HH:mm:ss",
    CultureInfo.InvariantCulture
);