ACC97: Modifying Linked Exchange Tables in Microsoft Access (167660)

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Linked Microsoft Exchange data is best suited as a read-only reference or as lookup information in your database. For example, you can use the Global Address Book to look up e-mail names for message recipients, or you can use Calendar information to view existing appointments and identify schedule conflicts.

However, if you want to modify data in the linked table, the following sections discuss some of the limitations you will encounter.

Adding New Records

When you link a Microsoft Exchange folder in your database, you have no choice of which fields to display in the table. The subset of fields that appear in your table are pre-programmed in the Microsoft Messaging Driver, Msexch35.dll, which manages the connection between Microsoft Access and Microsoft Exchange.

When you add a new record to the table, some fields produce the following error message when you try to enter data:

You cannot update these fields in Microsoft Access; however, once you identify the fields, you can simplify your data entry by hiding those columns as follows:

1. Open the linked table in Datasheet view.
2. Place the insertion point in a column that does not allow updating.
3. On the Format menu, click Hide Columns. Note that the column is no longer visible.
4. Repeat steps 2 and 3 for each column you want to hide.

To display the columns again:

1. Open the linked table in Datasheet view.
2. On the Format menu, click Unhide Columns.
3. In the Unhide Columns dialog box, click to select the check box for those columns you want to display again.
   
   NOTE: You can also click to clear the check box for any columns you want to hide.
4. Click Close.

Also, if you want Microsoft Outlook to use a specific form to display your new record, you must enter the correct data in the Message Class field. The Message Classes for the standard Microsoft Outlook folders are:

   Folder       Message Class
   ----------------------------
   Calendar     IPM.Appointment
   Contacts     IPM.Contact
   Inbox        IPM.Note
   Journal      IPM.Activity
   Notes        IPM.StickyNote
   Tasks        IPM.Task
				

Modifying Records

You cannot modify any records in a linked Microsoft Exchange table. The Microsoft Messaging Driver is designed only for reading existing records and adding new ones.

Deleting Records

When you delete a record from a linked Microsoft Exchange table, the record is immediately and permanently deleted. You cannot use the Undo command to restore the record, and it does not appear in the Deleted Items folder in Microsoft Exchange.

Use caution, and be sure that you really want to delete a selected record before you actually delete it.

You can work around this behavior in several ways:

• If you are using Microsoft Access security in your database, you can set permissions for the linked table so that deleting records is not allowed. This safeguards against accidental deletion of a record at the table level.
• If you are using a form based on the linked Microsoft Exchange table, you can set the form's AllowDeletions property to False. This will prevent anyone from accidentally deleting a record using the form; however, you can still delete records directly from the table or a query.
• If you are using a form based on the linked table, and you want to allow users to delete records, you can set the OnDelete property of the form to a macro or event procedure that prompts a user to confirm the deletion. For example:
  
  NOTE: This example assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to the "Building Applications with Microsoft Access 97" manual.
  

        Private Sub Form_Delete(Cancel As Integer)
        ' Display a custom dialog box to confirm deletion.
        If MsgBox ("Are you sure you want to delete this record?", _
                   vbOKCancel) = vbCancel Then
           Cancel = True
        End If
        End Sub