Gábor Boskovits <boskov...@gmail.com> writes:
> P
>
> Clément Lassieur <clem...@lassieur.org> ezt írta (időpont: 2018. júl. 29.,
> V 14:01):
>
>> Danny Milosavljevic <dan...@scratchpost.org> writes:
>>
>> > Hi Tatiana,
>> >
>> > On Sun, 8 Jul 2018 21:48:32 +0200
>> > Tatiana Sholokhova <tanja201...@gmail.com> wrote:
>> >
>> >> Do you have ideas on how to
>> >> implement tuple comparison and other routines in SQL and guile in a
>> >> convenient and flexible way?
>> >
>> > sqlite3 supports row values, so the comparison can be
>> > written like this:
>> >
>> > select * from foo where (a,b,c) = (2,'foo',3);
>> >
>> > It even supports NULLs for wildcards, though it's a little more
>> complicated:
>> >
>> > select * from foo where coalesce((a,b,c) = (2,NULL,3), 1) = 1;
>> >
>> > The sqlite C interface doesn't support parameter bindings for the entire
>> > row, though, so you'd have to specify 3 values.
>> >
>> > This works:
>> >
>> > (sqlite-exec db "select * from foo where (a,b,c) = (" 2 "," "foo" ","
>> 3 ");")
>> >
>> > but this doesn't work, unfortunately:
>> >
>> > (sqlite-exec db "select * from foo where (a,b,c) = " '(2 "foo" 3) ";")
>> >
>> > See also https://www.sqlite.org/rowvalue.html
>>
>> With the '<' operator, it doesn't give the results we are looking for, I
>> think.
>>
>> For example:
>>
>> select (0,1) < (1,0); -- returns 1
>> select (0,0) < (0,1); -- returns 1
>>
>
> This is working as expected. Actually this:
> (a,b)<(c,d) is a shortcut for a<c or (a=c and b<d).
>
> In both cases, we'd want it to return 0.
>>
>
> How do we use it? Why this is the expected result?
>
>
>> I think we should use:
>>
>> select (0 < 1) and (1 < 0); -- returns 0
>> select (0 < 0) and (0 < 1); -- returns 0
>>
>
> Could you please clarify which numbers are the placeholders for which
> quantities?
>
>>
>> instead, for the pagination borders code.
Actually, forget what I said, I was wrong ;-)
