The row_number() window function can be used without order by in over to arbitrarily assign a unique value to each row.
SELECT ROW_NUMBER() OVER ()
FROM …Related
Other forms:
row_number() over(order by …),rank(),dense_rank(),percent_rank(),cume_dist().Product specific forms:
rownum(pseudo column).
Normative References
The row_number() window function is defined in ISO/IEC 9075:2016-2 as part of optional feature T611. Using row_number() without order by is part of optional feature T612.
