格式异常：字符串未被识别为有效的DateTime

Question

hi I have method for getting the values form database and representing those values in chart controls..

and this is the method...

      public static void Hourlyattendence(System.DateTime startdate, System.DateTime enddate, string StartHour, string EndHour,
                                           out string[] Hours, out int[] Accepted, out int[] Refused)
     {
         int hours = 1 + int.Parse(EndHour) - int.Parse(StartHour);

         Hours = new string[hours];
         Accepted = new int[hours];
         Refused = new int[hours];

         int result = 0;

         for (int i = 0; i < hours; i++)
         {
             Accepted[i] = 0;
             Refused[i] = 0;
             Hours[i] = string.Format("{0:00}", int.Parse(StartHour) + i);
         }

         const string sql = @"SELECT COUNT('x') AS numVisits, visit_Status as Status, SUBSTRING(visit_Time,1,2) as visitHour
                              FROM visits
                              WHERE visit_Date BETWEEN @startdate AND @enddate
                              AND SUBSTRING(visit_Time,1,2) between @StartHour and @EndHour
                              GROUP BY SUBSTRING(visit_Time,1,2), visit_Status";

         var hourstable = new DataTable();

         using (var conn = new MySql.Data.MySqlClient.MySqlConnection(connectionstring))
         {
             conn.Open();

             var cmd = new MySql.Data.MySqlClient.MySqlCommand(sql, conn);

             var ds = new DataSet();
             var parameter = new MySql.Data.MySqlClient.MySqlParameter("@startdate", MySql.Data.MySqlClient.MySqlDbType.DateTime);
             parameter.Direction = ParameterDirection.Input;
             parameter.Value = startdate;
             cmd.Parameters.Add(parameter);

             var parameter2 = new MySql.Data.MySqlClient.MySqlParameter("@enddate", MySql.Data.MySqlClient.MySqlDbType.DateTime);
             parameter2.Direction = ParameterDirection.Input;
             parameter2.Value = enddate;
             cmd.Parameters.Add(parameter2);

             var parameter3 = new MySql.Data.MySqlClient.MySqlParameter("@StartHour", MySql.Data.MySqlClient.MySqlDbType.DateTime);
             parameter3.Direction = ParameterDirection.Input;
             parameter3.Value = StartHour;
             cmd.Parameters.Add(parameter3);

             var parameter4 = new MySql.Data.MySqlClient.MySqlParameter("@EndHour", MySql.Data.MySqlClient.MySqlDbType.DateTime);
             parameter4.Direction = ParameterDirection.Input;
             parameter4.Value = EndHour;
             cmd.Parameters.Add(parameter4);

             var da = new MySql.Data.MySqlClient.MySqlDataAdapter(cmd);

             da.Fill(ds);
             try
             {
                 hourstable = ds.Tables[0];

             }
             catch
             {
                 hourstable = null;
             }
         }
         if (hourstable != null)
         {
             for (int i = 0; i < hourstable.Rows.Count; i++)
             {
                 if (int.TryParse(hourstable.Rows[i]["numVisits"].ToString(), out result) && int.TryParse(hourstable.Rows[i]["visitHour"].ToString(), out hours))
                 {
                     hours -= int.Parse(StartHour);
                     if (hourstable.Rows[i]["Status"].ToString().ToUpper() == "ACCEPTED")
                     {
                         Accepted[hours] = result;
                     }
                     else
                     {
                         Refused[hours] = result;
                     }
                 }

             }

         }

     }

and i am calling above method in the below code ...and this is where i am representing the data in chart controls....

    private void KpiHourlAttendenceForm_Load(object sender, EventArgs e)
    {
        Drawkpihourlyattendence(dtpStartDate.Value, dtpEnddate.Value);
    }

    public void Drawkpihourlyattendence(DateTime startdate, DateTime enddate)
    {
        try
        {
            KpiHourlyattaendencechart.Series.Clear();

            Series acceptedSeries = KpiHourlyattaendencechart.Series.Add("Accepted");
            Series rejectedSeries = KpiHourlyattaendencechart.Series.Add("Refused");

            string[] xValues;
            int[] yValues;
            int[] yValues2;

            KpiData.Hourlyattendence(startdate, enddate, "06", "22", out xValues, out yValues, out yValues2);

            //blah
           //blah
           ///blah
       }
       catch(FormatException e)
      {
            Console.WriteLine(e.Message);

       }    

got the exception : format Exception String was not recognized as a valid DateTime.

would any one pls help on this.....

Many Thanks in advance...

Answer 1

将开始/结束时间更改为整数SQL参数类型，并将SUBSTRING（visit_Time，1,2）转换为您在BETWEEN @StartHour和@EndHour中执行的行中的整数

Answer 2

StartHour and EndHour are not DateTime .

Additionally, as @Ryan Wright pointed out, your between filter isn't going to work as expected with strings.

Answer 3

我认为您必须更改@StartHour和@EndHour的参数类型，因为它们是字符串。