Losing Data in a Shared Workbook

Subscriber Karen Havens described a problem in which a shared workbook, stored on a company network, periodically loses all the data it previously contained. In trying to track down the problem Karen did tests where she and her coworkers tried to open the file at the same time and save it at the same time, but all the tests left the data intact. Still, she reports that there are times when the workbook data is simply erased; wiped clean.

This problem is, perhaps, a prime example of why many people refuse to trust shared workbooks in Excel. Many folks have shared experiences where data has become corrupted, information is overwritten, or data just outright disappears. All the problems were traced to the fact that a workbook was shared, and the problems went away when the sharing was turned off.

This leads to the first suggestion: don't share the workbook. If you "unshared" it, then only a single person can open the workbook at a time, which reduces complexity and decreases the chances of corruption. If the data contained in the workbook is extensive and it must be shared among multiple users, consider converting to a program that is designed for better data integrity in a multi-user environment, such as Access.

If this is not possible, consider turning on Track Changes in Excel (on the Advanced tab of the Share Workbook dialog box) so that a change history is maintained. This allows you to see who last changed a workbook. If you open the workbook and find the data missing, checking the change history may actually disclose that the data was deleted--probably inadvertently--by a user.

Of course, it is possible that the change history may not provide the information that you hope it will. The reason that sharing a workbook can lead to data corruption is the way in which Excel allows users to work with data. In a program such as Access, data is fetched and worked with on a record-by-record basis. While the record is in use by a user, no other user can make changes to the record, but they can make changes to other records.

In Excel, the entire workbook is transferred to the user's computer, not just a single record from the data in the workbook. In a shared-workbook scenario, this means that multiple copies of the workbook are actually open at the same time, and Excel is charged with resolving potential conflicts in data. Consider the following scenario:

• User 1 opens the workbook, which means that a copy of the workbook now resides in his system memory.
• Ten minutes later User 2 opens the shared workbook. This version, now residing in the memory of User 2's system, does not contain any of the changes done during the last 10 minutes by User 1.
• Five minutes later User 2 saves the shared workbook, but continues working.
• Two minutes later User 3 opens the shared workbook. This version is the one that User 2 just saved, and doesn't include anything done by User 1 or any additional changes made by User 2 since last saving.
• Thirteen minutes later, all three users save their versions of the shared workbook and exit Excel.

In this thirty-minute scenario, can anyone tell which of the users' changes are saved in the final version of the workbook? Which changes should be saved? When you consider the ramifications of such a scenario (and this scenario is not uncommon), then you can see why many people suggest not using Excel in a shared environment.