Q241818: PRB: Calculated Field Contents Cannot be Modified by ADO

Article: Q241818
Product(s): Microsoft Visual Basic for Windows
Version(s): 2.0,2.01,2.1,2.1 SP1,2.1 SP2,2.5,2.6,5.0,6.0,6.5 Service Pack 4 and later,7.0
Operating System(s): 
Keyword(s): kbADO kbDatabase kbVBp600 kbGrpDSVBDB kbGrpDSMDAC kbDSupport kbADO210sp2 kbCodeSnippet
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
- ActiveX Data Objects (ADO), versions 2.0, 2.01, 2.1, 2.1 SP1, 2.1 SP2, 2.5, 2.6 
- Microsoft SQL Server versions 6.5 Service Pack 4 and later, 7.0 
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SYMPTOMS
========

Trying to modify the contents of a calculated field within an ActiveX Data
Objects (ADO) recordset, generates the following error:

  Runtime error '-2147217887(80040e21)' errors occurred.

CAUSE
=====

Each calculated field in an ADO recordset contains the following attributes:

- adFldUnknownUpdatable = False

  -and-

- adFldUpdatable = False

This indicates that the field cannot be modified.

RESOLUTION
==========

Here are two ways to work around this behavior:

- Use the Shape command to append a field into the ADO recordset.

  -or-

- Use the calculated field for display purposes only without modifying its
  contents.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

NOTE: Setting the adFldUnknownUpdatable and adFldUpdatable attribute flags is
provider dependent. If the provider does not set the flags as indicated
previously, you get a run-time error when you try to save the record.

The sample code below uses the publishers table in the pubs database that ships
with SQL Server.

Steps to Reproduce Behavior:

1. Start a new Visual Basic project. Form1 is created by default. Create a
  reference to the Microsoft ActiveX Data Objects 2.x Library.

2. Paste the following code in the General Declaration section of Form1:

  Option Explicit
  Dim con As New ADODB.Connection
  Dim rs As New ADODB.Recordset

  Private Sub Form_Load()

  ' Connection String to your SQL Server
  con.ConnectionString = "Provider=SQLOLEDB.1;Data Source=sequel;User ID=sa;Password=;Initial Catalog=pubs;"
  con.Open

  rs.CursorLocation = adUseClient
  ' Concatenate a character 'A' onto the value retrieved from the field pub_name.
  rs.Open "SELECT pub_name + 'A' AS PN FROM Publishers", con, adOpenStatic, adLockBatchOptimistic, adCmdText

  MsgBox rs.RecordCount

  Debug.Print rs(0).Attributes And adFldUnknownUpdatable, _
              rs(0).Attributes And adFldUpdatable

  rs(0) = "Hello" ' <----- ERROR OCCURS HERE

  MsgBox "Passed!"

  End Sub

3. The code prints FALSE for each of the flags, adFldUnknownUpdatable and
  adFldUpdatable, indicating that the field is known to be non-updateable.

NOTE: Calculated columns are also read-only in Data Access Objects (DAO) and
Remote Data Objects (RDO).

REFERENCES
==========

For more information on how to use the Shape command to append a field to an ADO
recordset, please refer to the following article in the Microsoft Knowledge
Base:

  Q223771 PRB: Appending Fields to a Recordset Generates an Error

(c) Microsoft Corporation 1999, All Rights Reserved.
Contributions by Ammar Abuthuraya, Microsoft Corporation


Additional query words: error -2147217887(80040e21)

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Keywords          : kbADO kbDatabase kbVBp600 kbGrpDSVBDB kbGrpDSMDAC kbDSupport kbADO210sp2 kbCodeSnippet kbMDAC260 kbADO260 
Technology        : kbVBSearch kbSQLServSearch kbAudDeveloper kbADOsearch kbADO210 kbADO201 kbADO200 kbADO210sp1 kbADO210sp2 kbADO250 kbADO260 kbZNotKeyword6 kbSQLServ700 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbSQLServ650SP4
Version           : :2.0,2.01,2.1,2.1 SP1,2.1 SP2,2.5,2.6,5.0,6.0,6.5 Service Pack 4 and later,7.0
Issue type        : kbprb

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