Microsoft Office

Part IV
Using Advanced Excel Features
Understanding File Reservations
Networks provide users with the ability to share information stored on other computer systems. Sharing
files on a network has two major advantages:
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It eliminates the need to have multiple copies of the files stored locally on user PCs.
It ensures that the file is always up-to-date. For example, a group of users can work on a single
document, as opposed to everyone working on his or her own document and then merging them
all together.
Some networks — generally known as client-server networks — designate specific computers
as file servers. On these types of networks, the shared data files are normally stored on the file
server. Excel doesn’t care whether you’re working on a client-server or a peer-to-peer network (where all the
PCs have essentially equal functions).
NOTE
Some software applications are multiuser applications. Most database software applications, for example,
enable multiple users to work simultaneously on the same database files. One user may be updating customer
records in the database, while another is extracting information for a report. But what if two users
attempt to change a particular customer record at the same time? Multiuser database software contains
record-locking safeguards that ensure that only one user at a time can modify a particular record.
Excel is not a multiuser application. When you open an Excel file, the entire file is loaded into memory. If
the file is accessible to other users, you wouldn’t want someone else to change the stored copy of a file that
you’ve opened. If Excel allowed you to open and change a file that someone else on a network had already
opened, the following scenario could happen.
Assume that your company keeps its sales information in an Excel file that is stored on a network server.
Esther wants to add this week’s data to the file, so she loads it from the server and begins adding new information.
A few minutes later, Jim loads the file to correct some errors that he noticed last week. Esther
finishes her work and saves the file. A while later, Jim finishes his corrections and saves the file. Jim’s file
overwrites the copy that Esther saved, and her additions are gone.
This scenario can’t happen because Excel uses a concept known as file reservation. When Esther opens the
sales workbook, she has the reservation for the file. When Jim tries to open the file, Excel informs him that
Esther is using the file. If he insists on opening it, Excel opens the file as read-only. In other words, Jim can
open the file, but he can’t save it under the same name. Figure 30.1 shows the message that Jim receives if
he tries to open a file that is in use by someone else.
FIGURE 30.1
The File In Use dialog box appears if you try to open a file that someone else is using.
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