Is there a formula that doesn't change current cell if false?

[wilmaloney]

I have a large spreadsheet and I regularly paste out a small section and get
many people to update fields. I then want excel to find this small section
(via Vlookup) and return the new updates. If the result in the main sheet is
false ie; current cell is not part of the small selection and cannot be
found, I want the cell to be unchanged. This allows me to keep the main sheet
updated as time permits.

 

[wilmaloney]

thanks for the reply, not sure if I was clear.
the main worksheet is my "Customer maintenance" worksheet, the small section
becomes the "todays work " worksheet. In both sheets I have a customer number
that I use in the vlookup formula. I then use vlookup to the find all the
entries of "todays work" in "Customer maintenance" and return the data that
has been updated. The problem I have is that in the "Customer maintenance"
sheet I have about 4000 records and I am only checking for about 20 records
at a time. If there is an existing entry in "customer maintenance" and it is
not part of "todays work" I don't want that cell to be changed. At the moment
as Vlookup can't find an entry it returns false , I would like it to see
FALSE but leave the cell unchanged?
Does that sound clear?