Note that you can have aggregates and scalars with the same name, as long as they have a different number of arguments.
This comes up with the min() and max() functions. The two-or-more argument versions of these functions are scalars. The one-argument version is an aggregate. On 3/9/17, Keith Medcalf <kmedc...@dessus.com> wrote: > > Ok, I see why you cannot use the same name. Queries of the form: > > select func(x) from y; > > would be ambiguous if there were both an aggregate func and a scalar func, > and the vdbe code generator uses the type of func (whether aggregate or > scaler) to determine whether to interpret the query as an aggregate > (returning a single value) or scalar (return one value per row). Simple > example, but there are many others where choosing the intended version of > func would change the query result possibly in a way other than intended. > > If you phrase a query that requires an aggregate function (such as select x, > func(y) from x group by x) then if func is scalar an error is thrown. If > you did a select x, func(y) from x and func is an aggregate function no such > problem arises as long as func is a valid aggregate for singletons. > > So unless something is definitely not working as intended, I think that you > should not be able to declare functions in both aggregate and scalar form > with the same name and the current code is correct. > >> -----Original Message----- >> From: sqlite-users [mailto:sqlite-users-boun...@mailinglists.sqlite.org] >> On Behalf Of Keith Medcalf >> Sent: Thursday, 9 March, 2017 15:33 >> To: SQLite mailing list >> Subject: Re: [sqlite] More built-in functions for basic math >> >> >> I get complaints from the compiler about duplicate definitions of macro's >> and functions ... >> >> As an aside, I am trying to walk db->aFunc as follows: >> >> sqlite3 *db = sqlite3_context_db_handle(context); >> Hash *h = &(db->aFunc); >> HashElem *p; >> FuncDef *d; >> char *functype; >> for (p = h->first; p; p = p->next) >> { >> d = p->data; >> functype = d->xFinalize ? "aggregate" : "scalar"; >> printf("%s %s %d %d\n", d->zName, functype, d->nArg, d- >> >funcFlags); >> while (d->pNext) >> { >> d = d->pNext; >> functype = d->xFinalize ? "aggregate" : "scalar"; >> printf("%s* %s %d %d\n", d->zName, functype, d->nArg, d- >> >funcFlags); >> } >> } >> >> but for functions which have both a scalar and aggregate form only the >> aggregate is showing up (actually, only the last version registered is >> showing up -- so which one shows up is scalar/aggregate is determined by >> which one was defined last). >> >> When I asked you about this you said that I simply need to register the >> function twice, once as an aggregate function and once as a scaler >> function, but it does not appear to actually keep the two different >> definitions. Is this a bug or working as intended? >> >> >> > -----Original Message----- >> > From: sqlite-users [mailto:sqlite-users-boun...@mailinglists.sqlite.org] >> > On Behalf Of Richard Hipp >> > Sent: Thursday, 9 March, 2017 13:08 >> > To: SQLite mailing list >> > Subject: Re: [sqlite] More built-in functions for basic math >> > >> > On 3/9/17, Keith Medcalf <kmedc...@dessus.com> wrote: >> > > >> > > note that fileio.c and shathree.c are inlined into shell.c, so in >> order >> > to >> > > remove them I have to modify shell.c to ifdef them out when I am >> > building. >> > > >> > >> > Seriously? I have no trouble loading the external fileio.c and >> > shathree.c extensions on top of the similar extensions that are built >> > into the shell. Nothing about the shell code has to change. What >> > part of that is not working for you? >> > >> > -- >> > D. Richard Hipp >> > d...@sqlite.org >> > _______________________________________________ >> > sqlite-users mailing list >> > sqlite-users@mailinglists.sqlite.org >> > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >> >> >> >> _______________________________________________ >> sqlite-users mailing list >> sqlite-users@mailinglists.sqlite.org >> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
