Re: GROUP BY

Hi Andy,

On Aug 21, 2005, at 11:39 AM, Seaborne, Andy wrote:

>> FWIW, my application (currently XML/XSLT oriented) is citation 
>> processing.  If I want a bibliography list in the form ...
>> Doe, J. (1999a) ...
>> ——— . (1999b) ...
>> ———. (2000) ...
>> .... I need to group and sort by author, then year.
>
> Bruce - could you expand on the need for GROUP BY in this specific 
> example? I don't see where an aggregate function is being used.
>
> In particular, in what way does sorting by author then by year not 
> achieve the effect of placing entries in the order described?  SPARQL 
> does have "ORDER BY"

Because I need to count the number of results in an author-year group.  
If there are more than one, I then need to number them (using a 
letter).  That's why "2000" does not have a suffix, but the two 1999s 
do.

Likewise, I need to be able to replace the name with the three 
em-dashes for all but the first in the author group.

So it helps to have the results sorted, but that's not enough, and it's 
a hassle if I then need to use XSLT (particularly 1.0) to do the 
additional processing.

I'll add that grouping is a common problem issue on the XSLT list, and 
the new grouping support in XSLT 2.0 arguably the most useful new 
feature.

Bruce