> To Pavel: My application reads the column types out in order to pretty > print the values - as mentioned by Tom - but also to generate a dialog > for entering new data (of course combined with INSTEAD OF TRIGGERs).
So as I see it: you have some universal code for displaying and inputing data. And you don't want to lessen scalability of your application by hard-coding the relation between column names and their data types. So you can create additional table that will contain this information. And I think this solution is better than just relying on declared type of columns - more straightforward and more understandable by somebody coming to your project in the future. Pavel On Thu, May 6, 2010 at 7:11 PM, Stefan Keller <sfkel...@gmail.com> wrote: > Thank you, Tom and Dan, for your constructive answers. > > To Pavel: My application reads the column types out in order to pretty > print the values - as mentioned by Tom - but also to generate a dialog > for entering new data (of course combined with INSTEAD OF TRIGGERs). > > I understand that it's difficult to implement result-types for > expressions in general. To me it would be enough if there would be at > least one way to assign result-types with a CAST "wrapper" as I have > mentioned before. > > Does anybody know whom to present this proposal in order remedy this > current inconsistency in SQLite? sqlite-dev? > > In the meantime I thought of a hack and to assign the result-type by > hand in the data dictionary after having created the VIEW. > Would this be a feasible work around? > > Yours, S. > > 2010/5/6 BareFeetWare <list....@tandb.com.au>: >> On 06/05/2010, at 2:51 PM, Dan Bishop wrote: >> >>> BareFeetWare wrote: >>>> >> >>>> I've had the same issue. In the end I had to parse my view functions in my >>>> own code and look for functions that give a particular type of result. So, >>>> for instance, round() gives an integer, round(..., 2) gives a real, >>>> concat() gives text. I also look for a cast(... as type) to use that >>>> declared type. It's fiddly and I would have hoped SQLite would have at >>>> least declared the type if a cast was present, but it seems not. >>>> >> >>> A CAST expression could be assigned a declared type >> >> Yes, that should be fairly easy to do in SQLite, simpler than my adding it >> in my own code (which then requires my own parser - not a trivial exercise). >> >>> but it would be difficult to implement it for expressions in general. Not >>> only would you have to declare a type for every function >> >> Yes, probably half the functions don't have a consistently returned type (eg >> length, concat). The ones that don't (eg coalesce) should just be left to >> return a null (unknown) type. The schema developer can simply wrap those >> expressions in a cast if they want a predetermined output type. >> >>> but you'd have to do it for operators as well, and what type should A * B >>> be if A is "SMALLINT" and B is "UINT"? >> >> I hadn't thought of operators. As far as I know, mathematical operators (* / >> + -) only work with integers and reals, Perhaps the result type could be set >> to "numeric" or some other superclass. Or, to get real fancy, if the two >> operands are declared integers, then the result is an integer; if one is >> real then the result is real. AFAIK SMALLINT and UINT are both treated by >> SQLite as integer, so the result would be an integer. >> >>> Should relational operators have a declared type of BOOLEAN? >> >> Good idea. >> >> Tom >> BareFeetWare >> >> -- >> Comparison of SQLite GUI tools: >> http://www.tandb.com.au/sqlite/compare/?ml >> >> _______________________________________________ >> sqlite-users mailing list >> sqlite-users@sqlite.org >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >> > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
