I got an error message, "There is already an open DataReader associated with this Connection which must be closed first.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: There is already an open DataReader associated with this Connection which must be closed first."
What did I do wrong? Here is the part of the code.

string searchProjectSQL="SELECT ProjectID, ProjectName, DateOfEvent FROM Project WHERE ProjectName ='" + ProjectName +"' AND DateOfEvent = '" +DateEvent+ "'";
Int32 intProjectID;
OleDbCommand searchProjectCommand = new OleDbCommand(searchProjectSQL,myConnection);
                ProjectDataReader = searchProjectCommand.ExecuteReader();

                if(ProjectDataReader.Read()==true)
                {
                    intProjectID = Convert.ToInt32(ProjectDataReader["ProjectID"].ToString());

                    string foreignRegiProjectSQL = "UPDATE Registration SET ProjectID ="+intProjectID+" ";
                    foreignRegiProjectSQL += @"WHERE (ProjectID IN (SELECT ProjectID FROM Project ";
                    foreignRegiProjectSQL += @" WHERE ProjectName='" +ProjectName+ "' AND ";
                    foreignRegiProjectSQL += @"DateOfEvent='"+DateEvent+"'))";

                    string UserProjectPSQL = "UPDATE UserProject SET UserID="+UserID+", ";
                    UserProjectPSQL += @"ProjectID =" +intProjectID+ ", CreateDate='"+DateTime.Now.ToString()+"' ";
                    UserProjectPSQL += @"WHERE (ProjectID IN (SELECT ProjectID FROM Project ";
                    UserProjectPSQL += @"WHERE ProjectName='"+ProjectName+"' AND ";
                    UserProjectPSQL += @"DateOfEvent='"+DateEvent+"'))";

                    OleDbCommand foreignRegiProjectCommand = new OleDbCommand(foreignRegiProjectSQL,myConnection);
                    OleDbCommand UserProjectPCommand = new OleDbCommand(UserProjectPSQL,myConnection);
                    foreignRegiProjectCommand.ExecuteNonQuery(); UserProjectPCommand.ExecuteNonQuery();
                }
                ProjectDataReader.Close();

Thanks,

Once you are done with your initial query, you need to close the reader. It looks like you are using the reader only to get one value so close it right after that.

intProjectID = Convert.ToInt32(ProjectDataReader["ProjectID"].ToString());
ProjectDataReader.Close();
//proceed with code and your following NonQuery won't fail.

Peter
------------------------------------------------------
Work smarter, not harder.

How about this case? If I put on a couple of ExecuteReaders sequentially, they will fail. For example,
OleDbCommand searchProjectCommand = new OleDbCommand(searchProjectSQL,myConnection);
                OleDbDataReader ProjectDataReader = searchProjectCommand.ExecuteReader();

                OleDbCommand searchLocationCommand = new OleDbCommand(searchLocationSQL,myConnection);
                OleDbDataReader LocationDataReader = searchLocationCommand.ExecuteReader();


                if(ProjectDataReader.Read()==true) && LocationDataReader.Read() == true)
{
..........

Sure they'll fail, because you can only have one datareader open at a time. What's your point? Are you asking how to do this? How to open two data set's at the same time? The answer will most likely be to use a DataSet. By using a dataset, you can create multiple datatables that are disconnected instead of a single connect datareader.

Peter
------------------------------------------------------
Work smarter, not harder.

Thanks!!!