Sets in the Where Clause and Autoexists

I don’t usually blog about bugs, but there are some cases where the dividing line between what’s a bug and what is ‘by design’ is unclear – and in these cases, a warning to the user community is always helpful. This is one of those cases…

The other day I was talking to Peder Ekstrand of DSPanel and he showed me a pair of queries running on SSAS 2008 that had him confused and to be honest, to me looked clearly buggy. I managed to repro the behaviour on Adventure Works on 2008 (friends reproed it on 2005 too) and here are my queries. The first one returns a single cell containing the value $14,477.34, the value of Internet Sales on July 1st 2001, as you’d expect: