Cannot access the return value of a PostgreSQL function using ADO

Hi,

I have a Postgres function

CREATE OR REPLACE FUNCTION updateconfigitem(inputkey character varying,

                                            inputvalue character varying,

                                            modifier character varying)

  RETURNS integer AS

$BODY$

BEGIN

    UPDATE  configitems

    SET _value          = inputvalue,

        _modifier       = modifier

    WHERE _key = inputkey;

    RETURN 1;

EXCEPTION

   WHEN others THEN

      RETURN 33;

END;

$BODY$

  LANGUAGE plpgsql VOLATILE

  COST 100;

I call it from a VB6 program using ADO

Dim objCmd As ADODB.Command

Dim colParams As ADODB.Parameters

Dim objParam As ADODB.Parameter

Dim lngRETURN_VALUE As Long

Dim strSQL As String

    ' Set connection properties and open

    Set objCon = New ADODB.Connection

    objCon.ConnectionString = "DATABASE=MYdatabase;UID=MyUser;PWD=Mypassword;DSN=PostgreSQL30"

    objCon.CursorLocation = adUseClient

    objCon.Open

    Set objCmd = New ADODB.Command

    ' Set command properties

    With objCmd

        Set .ActiveConnection = objCon

        .CommandTimeout = m_lngCommandTimeout

        .CommandText = "updateconfigitem"

        .CommandType = adCmdStoredProc

        Set colParams = .Parameters

    End With

    ' Define stored procedure params and append to command.

    colParams.Append objCmd.CreateParameter("RetVal", adInteger, adParamReturnValue, 0)

    colParams.Append objCmd.CreateParameter("inputkey", adVarChar, adParamInput, 50)

    colParams.Append objCmd.CreateParameter("inputvalue", adVarChar, adParamInput, 255)

    colParams.Append objCmd.CreateParameter("modifier", adVarChar, adParamInput, 255)

    ' Specify input parameter values

    colParams("inputkey") = "colour"

    colParams("inputvalue") = "Green"

    colParams("modifier") = "mg"

    ' Execute the stored procedure

     objCmd.Execute

End Sub

When I execute I get error

“Run-time error '-2147467259(80004005)': ERROR: could not determine data type of parameter $4; Error while executing the query”

If I remove the line creating the return parameter

colParams.Append objCmd.CreateParameter("RetVal", adInteger, adParamReturnValue, 0)

the program works OK. I use the same type of ADO definition to call MS SQLServer stored procedures and I can pick up the return value.

What do I need to do to get the Postgres Function Return Value?

I am developing on a Windows 7 Professional (SP1) operating system. Using Microsoft Visual Basic 6.0(SP6), Microsoft ActiveX Data Objects 2.7 Library and PostgreSQL version: 9.5.4

Regards,

Mick Griffin

Software Engineer

BTS Holdings PLC

DDI: +44 (0)20 8401 9003           Fax: +44 (0)20 8401 9101

http://www.bts.co.uk