如何将DateTime数据类型与DateTime.Now进行比较

Question

I have a variable from a datatable using the datetime datatype. This datatype is the "scheduledTime" column. I am trying to compare the datatime variable to the system clock which would return a difference background color on my table. I am not getting any results with my code and I to get some guidance... Also i am not sure how to define the "scheduledTime" datetime variable in my condition

Here is the condition:

if scheduledTime is 0-15mins late then background color red..

if scheduledTime is 15min-30mins late then background color yellow..

if scheduledTime is 30mins-2hours late then background color green..

//Row Rendering event
public void Row_Rendering()
{
    DateTime currentTime = DateTime.New();
    DateTime scheduledTime = "SCHD DTM"   //<--- this is the name of the column from the table

    int i = DateTime.Compare(scheduleTime,currentTime); 
    if (i <= 0.25)
    {
        Style.SelectionBackColor = Color.Red;
        ForeColor = Color.White;
    }
    else if (i > 0.25 && i <=0.5)
    {
       Style.SelectionBackColor = Color.Yellow;
       ForeColor = Color.Black;
    }
    else if (i > 0.5 && i <=2)
    {
       Style.SelectionBackColor = Color.Green;
       ForeColor = Color.White;
    }
}

Answer 1

In order to get the difference in minutes between two DateTime values, you can subtract the two DateTimes then call TotalMinutes on them:

double differenceInMinutes = (currentTime - scheduledTime).TotalMinutes;

You can then use differenceInMinutes for your computations accordingly:

if (differenceInMinutes <= 15) then
Style.SelectionBackColor = Color.Red;
ForeColor = Color.White;

else if (differenceInMinutes > 15 & differenceInMinutes <= 30) then
Style.SelectionBackColor = Color.Yellow;
ForeColor = Color.Black;

else if (differenceInMinutes > 30 & differenceInMinutes <= 120)
Style.SelectionBackColor = Color.Green;
ForeColor = Color.White;

UPDATED

Below's a sample on how to get the DateTime value from a DataTable. Assuming that the DataTable is stored in a variable named myDataTable and you are currently on the first row (row index of 0):

DateTime scheduledTime = myDataTable.Rows[0]["SCHD DTM"];

Answer 2

Try to operate with TimeStan object like:

TimeSpan timeSpan = currentTime - scheduleTime; 

after that you can simply use timeSpan.TotalMinutes property or other Total... properties.

Answer 3

You can compare TimeSpan values directly

            DateTime currentTime = DateTime.Now;
            DateTime scheduledTime = dataReader.GetDateTime(0);

            TimeSpan timeDifference = scheduledTime - currentTime;
            if (timeDifference <= new TimeSpan(0, 15, 0)) //less 15m
            {
                Style.SelectionBackColor = Color.Red;
                ForeColor = Color.White;
            }
            else if (timeDifference <= new TimeSpan(0, 30, 0)) //15m - 30m
            {
                Style.SelectionBackColor = Color.Yellow;
                ForeColor = Color.Black;
            }
            else if (timeDifference <= new TimeSpan(2, 0, 0))//30m - 2hr
            {
                Style.SelectionBackColor = Color.Green;
                ForeColor = Color.White;
            }
            else // > 2hr
            {
                //:todo: create styles for time difference > 2 hr
            }