I used deductive reasoning more than SQL skills to guess this right 😀
I assumed Number 1 would return both columns, the other 3 would return only column 2 and number 4 would include one NULL (doesn't DISTINCT include one NULL?) so I assumed that ALL was the default and would therefore make 2 and 3 have identical results. But I guessed 😀
Is my explanation close to being right?
Peter Trast
Microsoft Certified ...(insert many literal strings here)
Microsoft Design Architect with Alexander Open Systems