Other questions have touched on this and offered solutions that are not viable for a very large data set. I have a formula like the following across 9 columns:
=IF(A1=A2, B2, "zz")
I then autofill about 3.5 million cells + copy -> paste values. Then I find and replace "zz" with "empty cell". However, finding and replacing a million or so "zz" strings is a very slow process. I'd rather not write anything there in the first place. So my question is, how to I write the following formula:
=IF(A1=A2, B2, 'leave cell alone and write nothing there at all')
Excel seems to be incapable of not touching a cell in case of FALSE (or TRUE for that matter).
The fact that the cell contains a formula already means that it is not truly empty. Common practice is to use an empty string, like
=IF(A1=A2, B2,"")
There are not many situations where this will be problematic, and if a problem arises, in most cases there are different techniques that can be applied.
Let NULL be the name of a cell that has "" in it, and BLANK be the name of a cell that is truly blank.
NULL is not truly blank; ISBLANK(NULL) will return FALSE. But note that '=' takes blank and null cells to be identical. So for any cell C1:
(C1="")
(C1=BLANK)
(C1=NULL)
will all return TRUE if C1 is truly blank OR if it contains "". (I find this simpler than using COUNTBLANK(C1)>0, which has been suggested elsewhere.)
