Question Re: When have EXCEPT and INTERSECT been introduced? in Technology Q&A

When have EXCEPT and INTERSECT been introduced?

VolkerBarth — Wed, 22 Sep 2010 15:41:41 GMT

While I'm about to leave ASA 8.0.3 behind, I made some comparisons with ASA 8.0.3.5574 and SA 12.0.0.2566 and accidently used EXCEPT and INTERSECT on ASA 8.0.3.

I had strongly expected a syntax error as I was absolutely sure both set operators were introduced with ASA9 (and they are not at all documented with ASA 8), but they work.

Just couldn't believe it: Have I deliberately - but unfounded! - left out these handy operators all those years when working with ASA 8 (while using them on newer version)?

Or have I missed a relevant piece of information?

But wait and calm down, Volker - they seem to get accepted syntactically in ASA 8.0.3 but don't seem to work correctly, i.e. a

SELECT pk_Column FROM table1 EXCEPT SELECT pk_Column FROM table2

does return the same resultset as without the EXCEPT clause or with an INTERSECT clause.

So it seems I have not missed an important feature...

My pulse is still accelerating...

Re: When have EXCEPT and INTERSECT been introduced?

Breck_Carter — Wed, 22 Sep 2010 16:17:14 GMT

Shh, don't tell anyone, but historically speaking the parser has been known to allow syntax for which no semantics exist 🙂

Re: When have EXCEPT and INTERSECT been introduced?

Former Member — Fri, 24 Sep 2010 13:32:43 GMT

In version 8, EXCEPT would not have been recognized as a keyword. In your example, it would have been treated as an identifier, specifically an alias for table1. The line:

SELECT pk_Column FROM table1 EXCEPT SELECT pk_Column FROM table2

would have been treated as a Transact-SQL batch returning two results sets. If you execute it in DBISQLC and then enter "resume", you'll see the second result set.

Re: When have EXCEPT and INTERSECT been introduced?

VolkerBarth — Fri, 24 Sep 2010 16:01:28 GMT

Ah, I see - I had not thought of the T-SQL batch feature but that makes it very reasonable that my sample statement worked whereas more complex ones (i.e. use this statement as a derived table) gives a syntax error. - Well, better SQL dialects use statement delimiters, don't they:)

Re: When have EXCEPT and INTERSECT been introduced?

VolkerBarth — Fri, 24 Sep 2010 16:10:26 GMT

Just to complete and answer the title question (whereas Bruce has answered the real question😞

As already stated in my question - both set operators were introduced with ASA 9.0.