On Mon, May 18, 2009 at 5:03 PM, Mitchell L Model <m...@acm.org> wrote: > I may be misreading the select-core diagram on > http://www.sqlite.org/lang_select.html but it appears that the down-arrow > that would allow a query without a FROM clause should not be there. Is it > really possible to have a SELECT with no FROM? If so, could someone provide > an example; if not, would someone maintaining the documentation make a note > of this? Thank you.
Yes. An use-case could be when you need to pass results to a function expecting table result data, but you actually have const data. Instead of having a select from some table (that must exist for the SQL to be valid), you can just issue a select with no "FROM" clause. sqlite> select 1,"Some Data" UNION select 2, "Some More Data"; 1|Some Data 2|Some More Data Note that although this is not standard SQL, some other engines also have similar features, for example, Oracle let's you do "SELECT 1 FROM DUAL", where "DUAL" means "not really from any table". In Oracle you could use it, for example, to get the server date/time so you could sync your client application clock. As SQLite is not a server, most pratical examples are for running user defined functions. The documentation could be ommiting this, but it's an esoteric enough feature. Regards, ~Nuno Lucas > -- > > --- Mitchell L Model _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
