Can not retrieve data from a ODBC connection to DB2 iSeries

Question

I've been trying to connect to a DB2 database on AS/400 for days. After I installed the IBM System i Access for Windows client I could create an ODBC data source from visual studio and when I click on "test connection" it is sucessful, However. executing a simple SELECT statement results in an infinite wait since database doesn't seem to respond to it: The code I'm using to connect and query is:

            OdbcConnection conn = new OdbcConnection(@"Dsn=TEST1;Uid=myuser;Pwd=mypwd;DBQ=mydb2");
            conn.Open(); 

            try
            {
                string cmmTxt = query;
                OdbcCommand cmd = new OdbcCommand(cmmTxt, conn);
                OdbcDataAdapter da = new OdbcDataAdapter(cmd);
                da.Fill(dset);
            }
            catch (Exception e)
            {
                Console.Write(e.StackTrace);
            }
            finally
            {
                conn.Close();
            }

The line where the execution stops responding is "da.Fill(dset);". BTW I'm using visual studio 2010 and I don't see any error message, but the code never finishes "waiting" after that line. Do you have any ideas? Thanks in advance

Answer 1

Setting LONGDATACOMPAT flag as 1 in the connection string worked for me.

[C#]
OdbcConnection con =
  new OdbcConnection("DSN=SAMPLE;UID=uid;PWD=mypwd;
  LONGDATACOMPAT=1;");

see the full explanation in the URL below

http://pic.dhe.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=%2Fcom.ibm.swg.im.dbclient.adonet.doc%2Fdoc%2Fr0011829.html

Answer 2

I'm not sure exactly what the problem is, but can you try using a data reader and see if that gives you better results?

OdbcConnection conn = new OdbcConnection(@"Dsn=TEST1;Uid=myuser;Pwd=mypwd;DBQ=mydb2");
string SQL = "SELECT COUNT(*) FROM MyTable";
using (OdbcCommand com = new OdbcCommand(SQL, connection, null))
{
    using (OdbcDataReader reader = com.ExecuteReader())
    {
        while (reader.Read())
        {
            var value = reader["MyColumn"];
        }
    }
}

Second, are you sure that your query will return in a reasonable amount of time? Do you have some tool which lets you run queries directly against the database (I'm not familiar with DB2, not sure if there is such a thing). Or is there a "profiler" that lets you "peek" at the database queries as they come in?

Since you don't show your query, I wonder if it's a very long-running query. How long did you wait for the query to return?

John