RE: ADQL v0.7.3

From: Clive Page <cgp-at-star.le.ac.uk>
Date: Tue, 2 Mar 2004 09:07:38 +0000 (GMT)


On Tue, 2 Mar 2004, Tony Linde wrote:

> The statement
> a / b / c / d
> is perfectly valid. It is up to the interpreter what is done with it.

I had been keeping my head down, but this makes me want to say that it is vital that we get this right, or at least make it clear what the right interpretation is.

Recently I got caught when translating some code from Fortran90 code into pl/pgSQL for Postgres (to implement HEALPix indexing). The expression "a / b / c"
has a clear Fortran interpretation of
"(a/b)/c"
but I discovered by getting wrong answers that in Postgres's version of SQL at least it is interpreted as
"a/(b/c)".
I found it _very_ hard to discover this in the Postgres manual, and in the SQL92 standard.

-- 
Clive Page
Dept of Physics & Astronomy,
University of Leicester,    Tel +44 116 252 3551
Leicester, LE1 7RH,  U.K.   Fax +44 116 252 3311
Received on 2004-03-02Z10:08:02