I found this a very understandable article. Assuming that everything that has been written is correct (and I have no reason to doubt that), this is very valuable information for me: it gives some understanding, plus practical, everyday examples with solutions. What else does someone wants to know ?

I am eager to read other people's comments.

Suggestion: see also the very valuable SSC article "TSQL LAB 2 - Writing Conditional WHERE Clauses", posted on February 27, 2008.

Leendert.