counting columns with text

Hi all,

I have 4 columns which can contain a string (a name) or can have a value <NULL>.

I want to create a 5th column where I count the number of strings in the 4 columns.

so for example:

Column A - Column B - Column C - Column D - Column Count

textA - textB - <NULL> - <NULL> - 2
<NULL> - textB - textC - textD - 3

So how do I populate this Column Count?

Thanks for any ideas!

Miika