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Garry Robinson
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has worked on 100+ Access databases. He is based in Sydney, Australia
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Is Your Database Corrupt
?
Chapter 5:
Backing up and Recovering Your Databases
Real World Microsoft Access Database
Protection and Security - ISBN 1590591267
Overview
If you are involved with a multi-user Access database, you must learn how to back up the database properly. This chapter shows you how to check whether everyone has logged off, how to log off all users, how to back up a database properly, how to back up information while people are using the database, and then, when that fateful day comes, how to recover your information. As you progress through these topics, you will learn a good use for XML and even find out which objects in your database take up the most space.
The download material for this chapter includes forms and Visual Basic for Application (VBA) examples, as follows:
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Functions to find out whether anyone is using the database. |
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A form to shut down the database at a set time. |
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A form that will safely back up a database by using the compact process. |
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A form that makes it easy for your users to compact their databases. |
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A form to unload all tables to comma-delimited format. |
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Two different ways to unload all tables to XML. |
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A form to back up all objects to text. |
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Special VBA recovery files that the text export procedures write automatically so that you can easily recover tables and objects. |
| Note |
To find the demonstration material, open the download database for your version of Access—for example, grMAP2002.mdb—and select Chapter 5. Before running any samples that involve data, you may need to relink the tables to the Northwind database on your computer. |
What You Must Know About Database Backups and Recoveries
Once again, I will provide two overviews about the important issues covered in this chapter. The first provides an overview that's applicable to all IT professionals, because everyone should be concerned with backups. The second summary covers extra topics that are relevant to the developer.
Overview for the DBA, IT Manager, and the Developer
Backing up and recovering an Access database would be easy if you could instantly get everyone to log off the database just before the system backup was due to commence. This process used to be called tape backup, but these days, databases can be backed up to all sorts of media, such as portable hard drives and DVD burners. If people are using the database when your system backup runs, you risk copying a database that is in an unstable state, which could cause you problems when you need to recover the database. This chapter provides solutions to that issue by showing you how to:
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Make sure that your database is ready for a system backup. |
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Show you how to back up your database to another location, including the new Access 2003 backup menu command. |
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Provide insight into good backup procedures. |
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Back up and recover individual tables while the database is in use by using both text and XML formats and objects that use the text format. |
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Recover relationships, menus, and import/export specifications. |
Of course, there are other reasons why you need to back up your databases, from computer equipment theft to the proverbial bus running over the laptop. One extremely good reason to use some of the object- and table-exporting software is that someone may unknowingly delete something or lock something while implementing database protection. Because problems like these always lurk around the corner, the more alternatives that you have, the more chances that you have to save lost information.
| Caution |
All the backup techniques described in this chapter can leave your security open to exploitation because you are creating yet more copies of the database and its objects for people to view. If you are serious about protecting and securing your backups, read Chapter 12 to find out how the operating system can protect the backup files. As part of this protection, you need to make sure that the Windows account that does the backups has write permissions for the backup directory. |
Overview for the Developer
The gist of this chapter is to make it easy for you to incorporate backup routines into your own applications, and most of the material covered in this chapter will require that you integrate the demonstration material into a database. Apart from the benefits of the different backup processes discussed, you'll learn other important things:
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Different ways to identify all the tables and objects in your database. |
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Another good use for XML. |
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The undocumented and powerful SaveAsText and LoadFromText methods. |
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Find out the very elusive facts about which are the biggest objects in your database, which is a very useful by-product of the object backup software in this chapter. |
If that sounds like a lot of work, rest assured that most of the forms and functions from the demonstration database should not require too much customization when you add them to your database.
Other Related Access Backup Topics
Click here for a collection of related links to other relevant pages
Backing up Multi-User Access Databases