Getting value with an anonymous block using ODP

Question

Hi all!
I have a problem I hope someone can help me with. I believe it to be a minor one. I am trying to imbed an anonymous block into my .net app and use it dynamically to get a value from the database depending on the values in a tables. Since my procedure is quite large I am displaying a small example proc for simplicity purposes. Basically I want to execute an anonymous block from my app that will return a value (not a row or rows) from the database. The code is below:
Private Sub test()
Dim cn As New OracleConnection(profileString)
Try
Dim sb As New System.Text.StringBuilder
sb.Append("Declare ")
sb.Append("v_maxnum varchar2(6); ")
sb.Append("Begin ")
sb.Append("Select max(to_number(email_address_id)) into ")
sb.Append("v_maxnum from CVWH14_CDRV_TEST.EMAIL_ADDRESS_TBL; ")
sb.Append("dbms_output.put_line(v_maxnum); ")
sb.Append("Exception ")
sb.Append("When Others ")
sb.Append("Then ")
sb.Append("dbms_output.put_line('Program run errors have occurred.'); ")
sb.Append("End; ")
Dim cmd As New OracleCommand(sb.ToString, cn)
With cmd
cmd.CommandType = CommandType.Text
Dim parm As New OracleParameter
parm.ParameterName = "v_maxnum"
parm.OracleType = OracleType.VarChar
parm.Direction = ParameterDirection.Output
parm.Size = 6
cmd.Connection.Open()
Dim ret As Object = cmd.ExecuteScalar()
Dim res As String = cmd.Parameters.Item(0).Value.ToString -- **Error is occuring here**
cmd.Connection.Close()
cmd.Dispose()
End With
Catch ex As Exception
MessageBox.Show(ex.Message, "Error")
'End If
If cn.State = ConnectionState.Open Then
cn.Close()
End If
End Try
End Sub
The exception error reads "Invalid Index 0 for this OracleParameterCollection with Count=0."
If I can figure out how to get a parameter value from the database via the anonymous block, I can apply the logic to the real application. Any help or direction I could receive would be greatly appreciated. Thanks for reading this post!

Answer 1

Thank you for responding. The code that I posted was just one of many ways I have tried. I retried the proc making just 2 changes:
Private Sub test()
Dim cn As New OracleConnection(profileString)
Try
Dim sb As New System.Text.StringBuilder
sb.Append("Declare ")
sb.Append("v_maxnum varchar2(6); ")
sb.Append("Begin ")
sb.Append("Select max(to_number(email_address_id)) into ")
sb.Append("v_maxnum from CVWH14_CDRV_TEST.EMAIL_ADDRESS_TBL; ")
sb.Append("dbms_output.put_line(:v_maxnum); ") -- !Changed this to a bind variable!
sb.Append("Exception ")
sb.Append("When Others ")
sb.Append("Then ")
sb.Append("dbms_output.put_line('Program run errors have occurred.'); ")
sb.Append("End; ")
Dim cmd As New OracleCommand(sb.ToString, cn)
With cmd
cmd.CommandType = CommandType.Text
Dim parm As New OracleParameter
parm.ParameterName = ":v_maxnum" -- !Changed this to a bind variable!
parm.OracleType = OracleType.VarChar
parm.Direction = ParameterDirection.Output
parm.Size = 6
cmd.Connection.Open()
Dim ret As Object = cmd.ExecuteScalar() -- !The error is now occuring here!
Dim res As String = cmd.Parameters.Item(0).Value.ToString
cmd.Connection.Close()
cmd.Dispose()
End With
Catch ex As Exception
MessageBox.Show(ex.Message, "Error")
If cn.State = ConnectionState.Open Then
cn.Close()
End If
End Try
End Sub
I am now getting the error message "Not all variables bound". Any more help or direction that you could throw my way would be greatly appreciated.