BareFeetWare wrote: > On 04/05/2010, at 3:14 AM, Stefan Keller wrote: > > >> But in SQLite if a view column comes from a function result or some >> computation, then the column type is NULL...!? It's not taking the >> result-type as mentioned in the manual >> (http://www.sqlite.org/lang_select.html) - even when I try to do a CAST in >> the projection clause, like this: >> >> SELECT id, name, CAST(salary + 10 AS INTEGER) "salaryplus10" FROM mytable; >> >> I mean that a VIEW should behave like a (read only) TABLE in any case. >> => Is there a way to give such columns a type anyway? >> > > 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, but it would be difficult to implement it for expressions in general. Not only would you have to declare a type for every function, 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"? Should relational operators have a declared type of BOOLEAN?
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