.net连接mysql

 myConnection = new MySqlConnection("server=192.172.0.39;Port=3306;Database=medicine;UserName=root;Password=root123");
                    myConnection.Open();                    string sql = "select d.DrugName,d.CommonName,d.Specification,dpi.ProduceTime,e.EnterpriseName,dl.TranspotTime," +
                               "e1.EnterpriseName ,e2.EnterpriseName  from" +
                               "drug_piats dpi left join drug d on dpi.DrugId= d.DrugId left join enterprise e on dpi.EnterpriseId=e.EnterpriseId" +
                              "left join drugliberary dl on d.drugId=dl.drugId left join enterprise e1 on dl.SendEnterpriseId= e1.EnterpriseId" +
                              "left join enterprise e2 on dl.ReceiveEnterpriseId= e2.EnterpriseId left join drugpack dp on d.DrugId = dp.DrugId" +
                              "where dp.SmallEPC=?epcValue";
                    MySqlCommand myCommand = new MySqlCommand(sql, myConnection);                    myCommand.Parameters.AddWithValue("?epcValue", epcValue);
                    myCommand.Parameters.Add(new MySqlParameter("?epcValue",MySqlDbType.VarChar,50));
                    myCommand.Parameters["?epcValue"].Value = epcValue;                    MessageBox.Show(epcValue);
                    
                    MySqlDataReader myDataReader = myCommand.ExecuteReader();
                   
                    while (myDataReader.Read())
                    {
                        lookupGoodInfo.DrugName = myDataReader["d.DrugName"].ToString();
                        lookupGoodInfo.CommonName = myDataReader["d.CommonName"].ToString();
                        lookupGoodInfo.Specification = myDataReader["d.Specification"].ToString();
                        lookupGoodInfo.ProduceTime = (DateTime)myDataReader["dpi.ProduceTime"];
                        lookupGoodInfo.EnterpriseName = myDataReader["e.EnterpriseName"].ToString();
                        lookupGoodInfo.TranspotTime = (DateTime)myDataReader["dl.TranspotTime"];
                        lookupGoodInfo.EnterpriseName1 = myDataReader["e1.EnterpriseName"].ToString();
                        lookupGoodInfo.EnterpriseName2 = myDataReader["e2.EnterpriseName"].ToString();
                        //lookupGoodInfo.SmallEPC = myDataReader["dp.SmallEPC"].ToString();
                        break;
                    }                    myDataReader.Close();
                    myConnection.Close();
这段代码那里有错啊