从字符串转换日期时间时转换失败

Question

I try reading data from SQL Server 2005 and filling it in a TableAdapter (also tried to user DataReader) but I keep getting this exception. The thing is that I get this error on some systems, that is I run my application peacfully on a system but on another system I get this exception.

The Code is:

public DataSetRef GetReportPumpControl(PumpInfo pump, DateTime start, DateTime end)
    {
        if (!OpenConnection())
            return null;

        m_Command.CommandText = "SELECT ref_dig_pumpcontrol, ref_energy, ref_datetime FROM [molisoftSchema].[Refresh] WHERE ref_pump_id = " + pump.ID + " AND ref_datetime BETWEEN '" + start + "' AND '" + end + "' ORDER BY ref_datetime ASC";

        SqlDataAdapter adapter = new SqlDataAdapter(m_Command);
        DataSetRef ds = new DataSetRef();
        adapter.Fill(ds, "RefreshPC");

        return ds;

        /*m_Reader = m_Command.ExecuteReader();

        LinkedList<PumpControlInfo> returnValue = new LinkedList<PumpControlInfo>();
        while (m_Reader.Read())
        {
            PumpControlInfo tempControl = new PumpControlInfo();
            tempControl.DateTime = (DateTime)m_Reader["ref_datetime"];
            tempControl.Energy = (double)m_Reader["ref_energy"];
            tempControl.PumpControl = (bool)m_Reader["ref_dig_pumpcontrol"];

            returnValue.AddLast(tempControl);
        }
        m_Reader.Close();
        return returnValue.ToArray<PumpControlInfo>();*/
    }

Please help me with this matter. Thanks in advance!

Answer 1

Kill 2 birds with 1 stone and parameterise your SQL (will guard you against SQL injection attacks):

m_Command.CommandText = "SELECT ref_dig_pumpcontrol, ref_energy, ref_datetime FROM [molisoftSchema].[Refresh] WHERE ref_pump_id = @pumpid AND ref_datetime BETWEEN @StartDate AND @EndDate ORDER BY ref_datetime ASC";

m_Command.Parameters.AddWithValue("@pumpid", pump.ID);
m_Command.Parameters.AddWithValue("@StartDate", start);
m_Command.Parameters.AddWithValue("@EndDate", end);

The problem was because the .NET start and end DateTime values are being serialised to a string to "hard code" into the SQL you were generating. However, this string representation could not be translated back into a valid datetime in SQL (you'd need to use a SAFE date format like yyyy-MM-ddTHH:mm:ss - so explicitly format those DateTimes before appending into the SQL statement). However, parameterisation is the far better solution which gets round these kinds of problems.

Answer 2

You should set your query values as parameters rather than just using string concatenation (and with it implicit conversion). Try:

m_Command.CommandText = "SELECT ref_dig_pumpcontrol, ref_energy, ref_datetime FROM [molisoftSchema].[Refresh] WHERE ref_pump_id = @id AND ref_datetime BETWEEN @start AND @end ORDER BY ref_datetime ASC";
m_Command.Parameters.AddWithValue("@id", pump.ID);
m_Command.Parameters.AddWithValue("@start", start);
m_Command.Parameters.AddWithValue("@end", end);

Aside from being better practice overall, this will use the conversion properties in place in parameters which are better designed for this sort of thing than implicit inline string conversion.