Returning multiple ref cursors from Oracle Procedure using DAAB & C#

Question

I want to return data from an Oracle procedure to populate some Label controls. The procedure accepts 26 input parameters (search variable) and returns 3 output cursors. I have been successful returning data from a procedure which returns a single ref cursor using OracleCommand, a DataAdapter, and a DataSet, but have been having all kinds of issues returning data from a procedure returning multiple ref cursors.

I was trying to use DAAB from the Enterprise Library, but had no success (original post). I now have gone back to an OracleCommand based off posts from Oracle and other dev sites. I am still returning zero rows. I can return the column names from my readers using "rdr_p_cursor_detail.GetName(0);", but When I try to return a value I get a "Operation is not valid due to the current state of the object." error.

        //Open the connection to Oracle.
        OracleConnection cn = new OracleConnection(ConfigurationHelper.ConnectionStringSlabProcedures);
        OracleCommand cmd = new OracleCommand();
        cn.Open();
        cmd.Connection = cn;


        try
        {

            //Set the command text (SQL) of the Oracle command to the stored procedure "getSlab", which returns slab details.
            cmd.CommandText = ConfigurationHelper.ProcuedurePackageSchema + "." +
                              ConfigurationHelper.ProcuedurePackageName + "." +
                              "getSlab";
            //...and specify the command as a stored procedure.
            cmd.CommandType = CommandType.StoredProcedure;


            //Add the input and output parameters.  
            cmd.Parameters.Add("rb_category", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("rb_category_value", OracleDbType.Varchar2).Value = slabID;
            cmd.Parameters.Add("rb_type ", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("rb_chem_value", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_inside_only", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_appl_pending", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_appl_soft_approved", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_appl_hard_approved", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_appl_mechanically", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_as_cast", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_as_dispoed", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_chem_match", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_near_match", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("txt_width_min", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_width_max", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_quality_min", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_quality_max", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_days_old_min", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_days_old_max", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_days_rev_min", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_days_rev_max", OracleDbType.Int32).Value = 0;
            cmd.Parameters.Add("txt_reviewer", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_excl_hr", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_excl_cr", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_excl_galv", OracleDbType.Varchar2).Value = string.Empty;
            cmd.Parameters.Add("cb_excl_tin", OracleDbType.Varchar2).Value = string.Empty;



            //Add the ref-cursors as output parameters
            OracleParameter p_cursor_detail = cmd.Parameters.Add("p_cursor_detail", OracleDbType.RefCursor);
            p_cursor_detail.Direction = ParameterDirection.Output;

            OracleParameter p_cursor_comments = cmd.Parameters.Add("p_cursor_comments", OracleDbType.RefCursor);
            p_cursor_comments.Direction = ParameterDirection.Output;

            OracleParameter p_cursor_grades = cmd.Parameters.Add("p_cursor_grades", OracleDbType.RefCursor);
            p_cursor_grades.Direction = ParameterDirection.Output;

            // Execute the command
            cmd.ExecuteNonQuery();


            // Construct an OracleDataReader from the REF CURSOR
            OracleDataReader rdr_p_cursor_detail = ((OracleRefCursor)p_cursor_detail.Value).GetDataReader();

            if (rdr_p_cursor_detail.Read())
            {

                //This would return an error if it was outside this if statement.
                //"Operation is not valid due to the current state of the object."
                OracleString oracleString1 = rdr_p_cursor_detail.GetOracleString(1);
                LabelSlabID.Text = oracleString1.ToString();

                //This correctly returns column name/header.
                //LabelSlabID.Text = rdr_p_cursor_detail.GetName(0);

            }
            else
            {
                LabelSlabID.Text = "No Data";
            }



            rdr_p_cursor_detail.Close();
            rdr_p_cursor_detail.Dispose();

            p_cursor_detail.Dispose();
            p_cursor_comments.Dispose();
            p_cursor_grades.Dispose();

        }
        catch (Exception e)

The truncated oracle procedure:

PROCEDURE getSlab         
(rb_category                  IN VARCHAR2
,rb_category_value        IN VARCHAR2
,rb_type                      IN VARCHAR2
,rb_chem_value            IN VARCHAR2                                
,cb_inside_only           IN VARCHAR2     
,cb_appl_pending          IN VARCHAR2   
,cb_appl_soft_approved    IN VARCHAR2   
,cb_appl_hard_approved    IN VARCHAR2             
,cb_appl_mechanically     IN VARCHAR2   
,cb_as_cast                   IN VARCHAR2   
,cb_as_dispoed            IN VARCHAR2   
,cb_chem_match            IN VARCHAR2   
,cb_near_match            IN VARCHAR2   
,txt_width_min            IN NUMBER
,txt_width_max            IN NUMBER
,txt_quality_min          IN NUMBER
,txt_quality_max          IN NUMBER
,txt_days_old_min         IN NUMBER
,txt_days_old_max         IN NUMBER     
,txt_days_rev_min         IN NUMBER
,txt_days_rev_max         IN NUMBER
,txt_reviewer             IN VARCHAR2         
,cb_excl_hr               IN VARCHAR2
,cb_excl_cr               IN VARCHAR2
,cb_excl_galv             IN VARCHAR2
,cb_excl_tin                  IN VARCHAR2
,cur_OUT OUT t_cursor1 
,cur_OUT1 OUT t_cursor2
,cur_OUT2 OUT t_cursor3) IS


 --All the queries and so forth are performed and data sent to temp tables.
  OPEN v_cursor1 FOR
        SELECT * FROM TABLE(CAST(g_slab_table AS getSlab_table));
    cur_OUT := v_cursor1;   

  OPEN v_cursor2 FOR
         SELECT * FROM TABLE(CAST(g_comment_table AS getComment_table));
    cur_OUT1 := v_cursor2;      

  OPEN v_cursor3 FOR
         SELECT * FROM TABLE(CAST(g_grades_table AS getGrades_table));
    cur_OUT2 := v_cursor2;      

Any ideas? I'm leaning towards improper reader use, but can't figure out what I'm missing. Thanks.

Answer 1

It appears to be the Oracle stored procedure. I modified the cursor output, hard-coding a selection from "dual", and the data and column headers are coming back good.

So...

Lesson 1) If you receive an error "Operation is not valid due to the current state of the object", your connection is closed or there are no rows of data being returned.

Lesson 2) Don't trust your procedure writers (if you aren't writing the db code yourself). Take the 30 minutes to review their code if you think your code should work. It can save you a dozen or so wasted hours :).

Thanks all.

Answer 2

I've been through almost the same scenario... The main problem was that there were no rows of data being returned. That can be checked by using:

    if(reader.HasRows)

The other thing that solved my problem was the use of

    reader.NextResult()

to get to the next returned (out) cursor.