Function - cmd.ExecuteScalar() problem

Question

I have never been able to .ExecuteScalar() so I must be missing something basic.
My stored procedure in package GTM.SETUP_PKG compiles without errors.
FUNCTION getLabBipk (p_labID IN VARCHAR2) RETURN NUMBER IS
return_value NUMBER;
CURSOR ret_cur IS SELECT bipk FROM gtm.lab WHERE labid=p_labid;
BEGIN
OPEN ret_cur;
FETCH ret_cur INTO return_value;
CLOSE ret_cur;
RETURN return_value;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END;
Here is my .NET invocation
OracleConnection conn = new OracleConnection(connString);
OracleCommand cmd = new OracleCommand("GTM.SETUP_PKG.GETLABBIPK",conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("P_LABID","JK-LAB");
cmd.Parameters.Add("BIPK",OracleDbType.Int32,DBNull.Value,ParameterDirection.ReturnValue);
conn.Open();
object bipk = cmd.ExecuteScalar();
conn.Close();
Running this, the cmd.ExecuteScalar() returns two errors:
ORA-06550 line string, column string:string...Cause: A PL/SQL compilation error has occurred.
PLS-00103 found 'string' but expected one of the following: 'string'"}
Thanks

Answer 1

There are two issues here.
1. There is a bug in the ODP.NET code that causes incorrect command text to be generated for stored functions if CommandType.StoredProcedure is used. To work around this problem, you can specify the complete command text and use CommandType.Text instead. For example,
You can change ....
cmd.CommandText = "SP";
cmd.CommandType = CommandType.StoredProcedure;
to ....
cmd.CommandText = "begin :1 := SP(:2); end;";
cmd.CommandType = CommandType.Text;
Of course, number of place holders depend on the number of parameters in your application.
2. ExecuteScalar function of OracleCommand returns the first column of the first row of the OracleDataReader that was created by executing either SELECT query or by a REF Cursor of a stored procedure/function. However, the function does not work if the stored procedure/function does not have a REF Cursor parameter. To work around this issue, you can use ExecuteNonQuery function of
OracleCommand class instead of ExecuteScalar.
I have filed two bugs (2585273 and 2585324) against ODP.NET and these bugs will be fixed in the next release.