Question

I’m looking for a one week interval, but any thing under 6 gives me:

 timeIn > DATE_SUB(NOW(), INTERVAL 1 WEEK)
Error:  Invalid attempt to Read when reader is closed.

 timeIn > DATE_SUB(NOW(), INTERVAL 6 WEEK)  //6 or anything above 6 and the query works
Error:  Invalid attempt to Read when reader is closed.

Here’s how I’m executing the query(this works, but when I change the INTERVAL from 6 to anything less I get the reader is closed error):

        string sql = "SELECT rooms.building, rooms.room, " +
        "users.FirstName, users.LastName, users.adUname,  " +
        "ingressegresslogs.timeIn, ingressegresslogs.timeOut, rooms.Id  " +
        "FROM rooms, users, ingressegresslogs  " +
        "WHERE  ingressegresslogs.RoomId = rooms.Id  " +
        "AND ingressegresslogs.timeIn > DATE_SUB(NOW(), INTERVAL 6 WEEK) "
        "AND ingressegresslogs.UserId = users.id " +
        "ORDER BY rooms.Id ASC, ingressegresslogs.timeIn ASC";        

    MySqlCommand cmd = new MySqlCommand(sql, conn);

    MySqlDataReader rdr = cmd.ExecuteReader();

EDIT: This query works from the mysql command line for and INTERVAL 1 WEEK just not in the C# code. 428 rows with data are returned

Here is the reader code, which may be where the problem is.

MySqlCommand cmd = new MySqlCommand(sql, conn);

            MySqlDataReader rdr = cmd.ExecuteReader();

            if (!rdr.HasRows)
            {
                rdr.Close();
                // EventLog.WriteEntry("IEReporter", "Database returned nothing", EventLogEntryType.Error, 234);           
            }

            while (rdr.Read())
            {

                try
                {
                    IELog queryResult = new IELog();

                    queryResult.RoomID = rdr.GetString("Id");
                    queryResult.FirstName = rdr.GetString("FirstName");
                    queryResult.LastName = rdr.GetString("LastName");
                    queryResult.ADUname = rdr.GetString("ADUname");
                    queryResult.Building = rdr.GetString("Building");
                    queryResult.Room = rdr.GetString("room");
                    queryResult.Ingresstime = rdr.GetDateTime ("timeIn");
                    //  timeOut might be null
                    if (Convert.IsDBNull(rdr["timeOut"]))
                        {

                            queryResult.Egresstime = new DateTime(1111, 1, 11);
                        }
                    else
                        {
                            queryResult.Egresstime = rdr.GetDateTime("timeOut");
                        }

                    queryResultList.Add(queryResult);

                }
                catch (Exception ex)
                {
                    Console.WriteLine("LogDAO build list:  " + ex);
                }
            }
            // Count rows
            //Console.WriteLine("Row Count: {0}", queryResultList.Count);

            rdr.Close();
            return queryResultList;

Answer 1

Seeing the code you posted, you probably want to return immediately after you determine there are no rows.

        if (!rdr.HasRows)
        {
            rdr.Close();
            // EventLog.WriteEntry("IEReporter", "Database returned nothing", EventLogEntryType.Error, 234);           
            return; // do this, or otherwise skip the read below
        }