问SqlException未被处理

EN

reader = command.ExecuteReader();

public void databaseQuestion()
{
    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
    SqlCommand command = 
       new SqlCommand((@"select T.TerritoryID,T.TerritoryDescription,avg(O.Freight)
                         from Employees E
                         inner join EmployeeTerritories ET on E.EmployeeID = ET.EmployeeID
                         inner join Orders O on E.EmployeeID = O.EmployeeID
                         where T.TerritoryDescription ='Bedford'
                         group by T.TerritoryID,T.TerritoryDescription,O.Freight") ,con);
    dbFile = filePath + @"\sqlFile.txt";

    SqlDataReader reader;

    con.Open();
    reader = command.ExecuteReader();

    using (StreamWriter file = new StreamWriter(dbFile, false))
    {
        while (reader.Read())
        {
            file.WriteLine(reader["T.TerritoryID"] + "\t" + reader["T.TerritoryDescription"]+ "\t" +reader["O.Freight"]);
        }
    }

    reader.Close();
    con.Close();
}