NODUPKEY and by _ALL_ with adjacent confusion?

[ResoluteCarbon]

Hi all SAS Users,

I am learning some courses provided by SAS, today when I reviewed the material, I saw this sentence.

I am from a country that English is a second language, so from what I know, adjacent means that two rows continuously in this case. So, if these two rows are not continuously, how come we exclude the totally duplicated rows?

Thank you in advance.

[Kurt_Bremser · Accepted solution]

"Adjacent" here means "adjacent after the sort".

[ChrisNZ]

The explanation would have been clearer (and obviously less confusing, since it confused you) if the word adjacent had been omitted. This word brings no value here.

It's probably a leftover from an explanation about the NODUPREC option, and should be removed here.