using System.Data.Odbc;

OdbcConnection odbcConn = new OdbcConnection("DRIVER={IBM INFORMIX 3.82 32 BIT};UID=myuser;PWD=mypass;DATABASE=adm;HOST=p660;SERVER=p660_on;SERVICE=1526;PROTOCOL=onsoctcp;CLIENT_LOCALE=ru_RU.1251;DB_LOCALE=ru_RU.1251;VMBCHARLENEXACT=0;CONNECTDATABASE=YES;EXCLUSIVE=0;CURSORBEHAVIOR=0;ENABLESCROLLABLECURSORS=0;ENABLEINSERTCURSORS=0;OPTIMIZEAUTOCOMMIT=1;OPTOFC=0;REPORTKEYSETCURSORS=0;NEEDODBCTYPESONLY=0;FETCHBUFFERSIZE=4096;DESCRIBEDECIMALFLOATPOINT=0;DONOTUSELVARCHAR=0;REPORTCHARCOLASWIDECHARCOL=0;");
odbcConn.Open();

OdbcCommand Cmd = new OdbcCommand("", odbcConn);
Cmd.CommandText = "Select num From user_tbl Where _id = ?";
Cmd.Parameters.Add("user", "myUser");

OdbcDataAdapter adp = new OdbcDataAdapter(Cmd);
adp.Fill(dataSet1);