Excel工作表中的空DateTime使用C＃添加到数据库

Question

I am having an issue with getting a value to pass into this variable. It is null coming from the excel file (using Aspose) but a DateTime doesn't except it. I added the DateTime ? to the variable but that doesn't help. I have tried a few ways that I know but none of them are working for the incoming null value. If the value is null, it has to stay null which the database allows for a null value. Can someone help me get this to work? Is there an easier way to go about this?

Try 1

EnterDate = Convert.ToDateTime(dr["EnterDate"]);
EnterDate = (EnterDate.HasValue) ? EnterDate : DateTime.Now;

Try 2

RepealedDate = (dr["RepealedDate"] == null) ? (DateTime?)null : Convert.ToDateTime(dr["RepealedDate"]);

Answer 1

Replace your second try with this:

DateTime? repealedDate = (dr["RepealedDate"] == null) ? 
    null : Convert.ToDateTime(dr["RepealedDate"]);

You can't cast null to DateTime? to solve the problem, you have to define the variable as being of type DateTime? .

Answer 2

I couldn't find a good solution on web. So I tried to handle it myself. I took data as string from Excel Sheet and then I controlled if its empty or not. If its I set it to null else I converted it to DateTime as below. This avoids me from exception that can happen in Convert function.

StartDate = dr[2].ToString().Trim();

if (StartDate != "")
   r.Data.StartDate = Convert.ToDateTime(StartDate);
else
   r.Data.StartDate = null;