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Q288106: HOWTO:Use UDL File for Hierarchical Commands in Data Environment

Article: Q288106
Product(s): Microsoft Visual Basic for Windows
Version(s): 2.0,2.1,2.1 (GA),2.1 SP1,2.1 SP2,2.5,2.5 SP1,2.6,6.0,6.0 SP3,6.0 SP4
Operating System(s): 
Keyword(s): kbDatabase kbDataEnv kbGrpDSVBDB kbDSupport kbMDACNoSweep kbADOsearch
Last Modified: 23-AUG-2001

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The information in this article applies to:

- Microsoft Visual Basic Enterprise Edition for Windows, versions 6.0, 6.0 SP3, 6.0 SP4 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
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SUMMARY
=======

This article explains how to use a Universal Data Link (UDL) file in place of a
connection string in the Data Environment with hierarchical or grouped Command
objects.

Normally, a UDL file can be used with a Data Environment Connection by changing
the ConnectionSource property manually to point to the UDL file by using the
"File Name=" argument, as follows:

  File Name=C:\MyFolder\MyUDLFile.udl

However, this approach does not work with Command hierarchies.

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

When a Data Environment Connection must service hierarchical Command objects,
the connection string that is entered by the developer at design time is
modified in a hidden manner at run time to use the MSDataShape data shaping
service provider in front of the originally specified provider (for example, the
Microsoft Jet or the SQLOLEDB provider).

Although the Data Environment handles this modification properly with an ordinary
connection string, the Data Environment does not handle this modification
correctly if the developer has manually specified a UDL file as the
ConnectionSource. The modified connection string that results is invalid, and,
although no error message may be generated, no data is retrieved.

You can work around this limitation and still rely on a UDL file by using two
Connection objects: one for "ordinary" Commands, and a second for hierarchical
or grouped Commands. This is demonstrated in greater detail in the following
example. The outline of steps is as follows:

1. Open the first connection for ordinary Commands by using the desired UDL
  file.

2. Create a new connection string based on this connection string, adding the
  arguments necessary to use the MSDataShape provider.

3. Assign this new connection string to the second connection for hierarchical
  Commands.

Example
-------

1. Create two identical Connections in your Data Environment and specify the
  connection information by using the Data Link Properties dialog box.

2. Create your ordinary Commands under Connection #1.

3. Create your hierarchical or grouped Commands under Connection #2.

4. Right-click on the Windows Desktop, in Microsoft Data Link choose New, and
  then specify the connection information to create a UDL file for your
  database.

5. Select Connection #1 in the Data Environment, and then change the
  ConnectionSource property in the Properties window to point to the UDL file
  by using the "File Name=" syntax shown earlier.

6. Select Connection #2, and then delete the existing contents of the
  ConnectionSource property. Note that you are now supplying this value
  programmatically.

7. Open the code window for the Data Environment, and then select the Data
  Environment's Initialize event.

8. Enter the following code for the Initialize event, adjusting the names of the
  Data Environment and the Connection objects as necessary:

  DataEnvironment1.Connection2.ConnectionString = "Provider=MSDataShape;Data " & DataEnvironment1.Connection1.ConnectionString

If your original connection string is

  "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyFolder\MyDatabase.mdb"

then the new connection string you have for your hierarchical Command object is:

  "Provider=MSDataShape;Data Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyFolder\MyDatabase.mdb"

9. Run and test your project.

REFERENCES
==========

For additional information, click the article numbers below to view the articles
in the Microsoft Knowledge Base:

  Q274536 HOWTO: Specify a UDL File as the Source of Connection Attributes for
  a VB Data Environment Connection Object

  Q244659 SAMPLE: How to Create a Data Link File with Windows 2000

Additional query words:

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Keywords          : kbDatabase kbDataEnv kbGrpDSVBDB kbDSupport kbMDACNoSweep kbADOsearch 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVB600 kbVB600SP3 kbVB600SP4
Version           : :2.0,2.1,2.1 (GA),2.1 SP1,2.1 SP2,2.5,2.5 SP1,2.6,6.0,6.0 SP3,6.0 SP4
Issue type        : kbhowto

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