Question

I have two tables called visits and members and i am getting the data by using following query..

 string sql=  @"SELECT member_Firstname, member_Lastname, member_Postcode,  
          visit_DateTime, visit_Status, visit_Logout_DateTime, visits.member_Id, visit_AlertMsg
          FROM members, visits
          WHERE members.member_Id = visits.member_Id
          AND members.member_Active LIKE 'y%'";

at here i am getting the visit_DateTime values with by using some comparisons with combobox values

    datatable dt = helper.getdata(sql)
     foreach (DataRow row in dt.Rows)
     {
         if (row["visit_Logout_DateTime"] != null)
         {
          DateTime dtlogout = DateTime.Parse(row["visit_Logout_DateTime"].ToString());
          if (dtlogout != null)
          {
            if (cbPeriod.Text == "Today")
            {
              newItem.lblTime.Text = dtlogout.ToString("HH':'mm':'ss");

            }
            else
              newItem.lblTime.Text = dtlogout.ToString("yyyy'-'MM'-'dd'  -  'HH':'mm':'ss");
          }
        }

     }

but i got the error at this line DateTime dtlogout = DateTime.Parse(row["visit_Logout_DateTime"].ToString());

error : string was not recognised as valid datetime (because of one value in that row is empty)

the row "visit_Logout_DateTime"

i have got the values of "visit_Logout_DateTime" like this….

firstname     lastname   postcode      visit_Logout_DateTime
-------------  --------   ---------      ---------------------
 rob            peter     hhd344h            
 peter         chan        hy78kjk         2011-09-08 12:09:08
 rock          sam        yudufg3746h      2011-08-08 09:08:45

i have tried that for checking the empty values of this visit_Logout_DateTime like i mentioned above..

but i have failed for chacking ever value is empty or not in that row…

how to check every value in this row (row[“visit_Logout_DateTime”]) is empty or not

would any one pls help me on this guys …

many thanks….

Answer 1

Instead of checking if the column is null, you should check if the contents of the column are null. You can do that by comparing it to DBNull.Value:

if (row["visit_Logout_DateTime"] != DBNull.Value)
{
    ...
}