计时器倒数SQL，ASP.NET C＃，JavaScript

Question

I'm trying to write code of timer countdown with javascript, sql , c# , asp.net.

the code now is like that:

<input type="text" id="auctionEndDate" value="<%=TargetDate()%>"  style="display:none"/> 
<script language="JavaScript" type="text/javascript">


TargetDate = "document.forms[0].auctionEndDate.value";
/*this is a property in code behind*/BackColor = "palegreen";
ForeColor = "navy";
CountActive = true;
CountStepper = -1;
LeadingZero = true;
DisplayFormat = "%%D%% Days, %%H%% Hours, %%M%% Minutes, %%S%% Seconds.";
FinishMessage = "the auction end"
</script>
<script type="text/javascript" language="JavaScript" 
src="http://scripts.hashemian.com/js/countdown.js"></script>
</script>

cs file:

public string TargetDate()
{
    SqlConnection connection = new SqlConnection("Data Source=tcp:***.*****.com;Initial Catalog=DB_***_****;User ID=***_*****_****_user;Password=******;Integrated Security=False;");
    string commandtext = "SELECT endTime FROM Timer";
    SqlCommand command = new SqlCommand(commandtext, connection);
    connection.Open();
    string tDate = (string)command.ExecuteScalar();
    connection.Close();
    return tDate;
}

Timer table desgin:

 ===============

 id

 endTime (nvarchar (150)

row in endTime : 12/31/2020 5:00 AM

and the result : NaN Days, NaN Hours, NaN Minutes, NaN Seconds.

when i change the desgin from nvarchar(150) to datetime i get the error : Unable to cast object of type 'System.DateTime' to type 'System.String'.

why i get the: NaN Days, NaN Hours, NaN Minutes, NaN Seconds.

what is the probleme? thanks.

Answer 1

To start, you need to change

TargetDate = "document.forms[0].auctionEndDate.value";

to

TargetDate = document.forms[0].auctionEndDate.value;

---

what i need to do to avoid the error when i change the type from nvarchar to datetime ?

Taking a guess here, since I'm really not a .NET programmer, you need to change

string tDate = (string)command.ExecuteScalar();

to

DateTime tDate = (DateTime) command.ExecuteScalar();

You can call GetType() on the return value ExecuteScalar() to see what type it really is.