Data Validation for Null

[Guest]

Hi,
i am new to data validation. I want to create a data validation so that
cells can not be Null. Should I use Custom and if so, how would I write the
formula. What is the best way to accomplish this?

 

[Guest]

Data > Validation > Custom

first clear the Ignore Blank checkbox
second enter the formula:

=A1<>""
for cell A1 for example

 

[Harlan Grove]

Data > Validation > Custom

first clear the Ignore Blank checkbox
second enter the formula:

=A1<>""
for cell A1 for example

....

That'd prevent editing a cell, clearing its contents while in Edit
mode, then trying to enter the result. It wouldn't prevent clearing
the cell - selecting the cell and pressing the [Delete] key - nor
would it force users to make entries.