Conditional Formatting to Lock a Cell

Can you use conditional formatting to decide to lock a cell?

Something similiar to:
(the following only pretends to be a photocopy of a formula, it is not a real formula, do not use near open flame or underwater)

IF A1=ISBLANK ... Lock A1, IF A1=ISNOTBLANK ... Lock B1

Thanks Shg, I was pretty sure that was the case.

I don't like the VBA store. It's like the IRS trying to sell you a used car. A bunch of uber-technical stuff I don't understand with all the pressure of being told, this IS exactly what you want. So you drive it off the lot and a block later the tires all roll off. You go back, and they say, OH, well... you said shiny and comfy interior... you didn't say you wanted it to turn LEFT.

But, I might have to learn it for this... I can't take the risk someone with minimal computer experience is going to accidently start erasing or writing over formulas and references to Important Things.

Originally Posted by shg

Not an option. If some calculation uses one or the other, and there's a priority (e.g., use A1 if not blank, else B1), then you can use CF in each to hide the unused value, making it pretty clear that it's being ignored.

Otherwise, a trip to the VBA store.

protect cells with formulas and lock the sheet!

if you auto protect a cell, what happens if someone puts in a wrong value, cell locks, it cant be changed, if it locks and you arnt there with the wrong value, sheet is useless anyway till you get back!!

By default I protect all formulas and lock the sheet before I let it go live, so only editable cells are available to end users!

Squiggler,

I am locking the sheet and they will only have a limited group of cells in which they can enter information... but SOMETIMES, they have to enter data in Column C but only if someone else did not enter information in Column B.

I don't want them to enter in information into Column C if Column B already has information in it... and they will, even if they are told not to, unless I lock them out of it.

VBA seems the best option here... and I'm halfway to a solution in that arena.