比较Datetime SQL Server和ASP.NET

Question

I'm making a function that would cancel an order only if it's within 60 minutes , what I was suggested is to compare the datetime value of the order to the current datetime.

        using (SqlConnection con = new SqlConnection(Helper.GetCon()))
        {
            con.Open();
            string query = @"SELECT * from [Order] where orderid = @id";
            using (SqlCommand cmd = new SqlCommand(query, con))
            {
                cmd.Parameters.AddWithValue("@id", id);
                using (SqlDataReader data = cmd.ExecuteReader())
                {
                    DataTable dt = new DataTable();
                    dt.Load(data);
                    foreach (DataRow dr in dt.Rows)
                    {
                        var supplier = new Supplier();
                        supplier.OrderDate = DateTime.Parse(dr["OrderDate"].ToString());
                    }
                }
            }
            return View();

So far I've only taken the datetime from the database, I was wondering how you can get the current datetime and get the difference in let's say minutes or hours so that I can make a conditional statement to allow or not allow the cancellation of an order. I'm fairly new to this and any help would be appreciated! Thank you!

Answer 1

使用DateDiff，将所选日期列与现在进行比较，并使用MINUTE差异：

SELECT DATEDIFF(MINUTE, OrderDate , getdate()) AS MinuteDiff from [Order] where orderid =123

Answer 2

If you must do it in the application rather than the SQL query, you can do something like:

var timeSinceOrder = DateTime.Now - supplier.OrderDate;

if(timeSinceOrder < TimeSpan.FromHours(1))
{
    //do stuff here
}

DateTime.Now gets the current time. Subtracting the order date from the current time returns a timespan that you can then compare to another timespan, in this case created by the function Timespan.FromHours.

Answer 3

You can also use DateTime.Compare method. Something like

If(DateTime.Compare(supplier.OrderDate, DateTime.Now) < 60)
{  
   //Enable Cancel/Delete Order
}