Oracle ExecuteNonQuery hangs on "Select for update nowait"

Question

I've been stuck on this for a few days now, and still can't figure out why :

I need to update a record in my Oracle database, before executing the Update query, I want to lock the data with a "SELECT x FOR UPDATE NOWAIT", but when calling the ExecuteNonQuery, my webservice hangs.

Executing the sql statement directly against the database works instantly. Here is the code :

                    OracleTransaction transact = OraDCS.BeginTransaction();
                    OracleCommand cmd = OraDCS.CreateCommand();
                    cmd.CommandText = string.Format("UPDATE FLIGHT_MANIFEST_PASSENGER SET ETAT_PASSAGER = '{2}',GATE_BOARDING = {0} WHERE REF_DOSSIER = '{1}'", ConfigurationManager.AppSettings["CodeMoyen"].ToString(), ref_dossier, etatPax);

                    OracleCommand blq = OraDCS.CreateCommand();
                    blq.CommandText = string.Format("SELECT * FROM FLIGHT_MANIFEST_PASSENGER WHERE REF_DOSSIER = '{0}' FOR UPDATE NOWAIT", ref_dossier);

                    bool blqOK = false;
                    try
                    {
                        blq.ExecuteNonQuery();
                        blqOK = true;
                    }
                    catch (Exception ex)
                    {
                        LogThreadSafe.Instance.Info("LanceSQL Error : " + blq.CommandText + " " + ex.Message);
                    }

                    if (blqOK)
                    {
                        try
                        {
                            cmd.ExecuteNonQuery();
                            transact.Commit();
                        }
                        catch (Exception ex)
                        {
                            transact.Rollback();
                            LogThreadSafe.Instance.Info("LanceSQL Error : " + blq.CommandText + " " + ex.Message);
                        }

                    }
                    else
                        transact.Rollback();

The lock is actually performed on the databse, but the program still hangs at this line :

blq.ExecuteNonQuery();

EDIT : Even after linking the transaction to the command I still experience the freeze. However, when I deploy my webservice on the server, and test it "live" rather than in debug on my dev machine, it works, any ideas?

Answer 1

You need to associate the commands with the transaction:

cmd.Transaction = transact;
blq.Transaction = transact;

I also highly recommend you don't build your query text by string concatenation, but use parameters instead in order to prevent SQL injection. For example:

blq.CommandText = "SELECT * FROM FLIGHT_MANIFEST_PASSENGER WHERE REF_DOSSIER = :pDossier FOR UPDATE NOWAIT";
blq.Parameters.Add(new OracleParameter("pDossier", ref_dossier));

Answer 2

i usually do if i must use a transaction:

OracleCommand cmd = OraDCS.CreateCommand();
OracleTransaction transact=cmd.Connection.BeginTransaction();
cmd.Transaction=transact;
cmd.CommandText = string.Format("UPDATE FLIGHT_MANIFEST_PASSENGER SET ETAT_PASSAGER = '{2}',GATE_BOARDING {0}WHERE REF_DOSSIER = '{1}'", ConfigurationManager.AppSettings["CodeMoyen"].ToString(), ref_dossier, etatPax);

maybe your transaction doesnt have a connection