Help Desk Chick,
I'll give you my standard blurb on having data in separate sheets. You can
explain this to the user who will likely (all of the following): 1) glaze
over and possibly not bother you again for quite a while, 2) continue to do
what he's doing with the multiple sheets, and 3) realize later on the wisdom
of your message and kneel at your feet.
Blurb on separating similar data across sheets:
There's a lot of Excel functionality that isn't available when similar data
is spread across multiple sheets, as well as across workbooks. Questions
abound where users already have data in separate sheets, and now want to
find certain data, summarize the data, etc. and there are no direct means to
do that.
If the layout of the data in the sheets will be the same (same column
headings), it is generally best to put all the data in a single sheet, with
an additional column for what originally was the various sheets. For
example, if you have a sheet for each month, put all the data in a single
sheet, with an additional column for month. An Autofilter can easily
reduce this consolidated sheet to the equivalent of one of the original
(month) sheets. Now you can sort in various useful ways, use Data -
Subtotals, easily make a pivot table to summarize the data, use database
functions (DSUM, COUNTIF, etc.).
If the separate sheets already exist, it's a straightforward one-time
project to combine them. Just make a sheet with the extra (month) column.
Now paste the records from the first sheet, and enter Jan into the month
column and copy down with the fill handle or copy/paste. Repeat for the
other sheets.