ASP.NET: change date format

how can I change my date format to:
2004-10-22 19:03:33


@SENT_DT_TM = '' the above date value ''
I need to pass this date format into my stored procedure so I can use in a datediff(hour, @SENT_DT_TM, DT_TM) function

Thanks in advance for any help.

VB Code:

Dim strDate As String = "10/22/2004 19:03:45"
 
        Dim dt As New DateTime
        dt = dt.Parse(strDate)
        MessageBox.Show(dt.ToString("yyyy-MM-dd H:mm:ss"))