Steven D'Aprano wrote:
On Sun, 6 Sep 2009 03:51:43 pm Greg Ewing wrote:
That said, I'm -0 on the idea overall. If someone actually needs it, it isn't particularly hard for them to write their own getany() function. There's a situation where the need to do this kind of
Nick Coghlan wrote: thing actually arises fairly frequently -- retrieving things from a relational database. Often you're expecting exactly one result from a query, but the API always gives you a sequence, which you then have to get the first item from. Doing that over and over again gets rather tedious.
If you're expecting "exactly one result", then surely it should be an error to receive more than one result? Rather than ask for "any" result and ignoring any unexpected extra items, I think it would be better to have a helper function that verifies you have got exactly one result.
Well, some queries return results without duplicate elimination, even though they are defined to return sets. If you really want to limit things in databases queries, the "LIMIT 1" clause is your friend, as the query optimizer knows it can stop as soon as its found something. Of course I don't know which query optimizers around now _use_ that knowledge to pick a query plan, but that leaves the info there if the next rev becomes limit-capable. Often when I just want to pick a single value from a column I use MIN or MAX (and fairly often when I need two distinct values I use both MIN and MAX). One trick to seeing a column is exactly a singleton is: SELECT MIN(something) FROM ... WHERE MIN(something) = MAX(something) --Scott David Daniels Scott.Daniels@Acm.Org