Well, I'll tell you the way it was used that was very painful for me. I just took a test on SQL that had statements such as...

SELECT *

FROM table1

NATURAL JOIN table2

(That is almost certainly not a true example from the test but "NATURAL JOIN" was explicitly part of the syntax used.)

I know there are some T-SQL pieces that I do not know or am not proficient at but I was certain I had never seen this syntax in books online, actual code, code examples, etc.

Anyway a good 1/4 or more had questions about NATURAL JOIN or natural joins in general so the test did not go well for me.

Books online specifically refers to three joins: INNER, OUTER and CROSS. There are a handful of references to a generic "natural join" in all of books online but I found no actual "NATURAL JOIN" syntax. Frankly I had never even heard the term -- and I hope I never hear it again.

I am fairly sure PL/SQL uses this syntax but I believe the test administrator did not make a mistake and give me a PL/SQL test.