Rich, Thanks. Simply writing the e-mail helped clarify things for me.
We?re trying to work out the logic of setting holiday_mode to an explicit 0 rather than an assumed 0. Its not quite as simple as setting it in a table as its linked back to a mobile app and the synchronisation logic is a little convoluted. If we can force holiday_mode to be set to either 0 or 1 then the problem goes away, which comes down to getting the design right. I think that this ?issue? we have is indicative of a poor DB design and wrong assumptions (bad pun) and we should fix that. Rob. > On 23 May 2015, at 17:06, Rich Shepard <rshepard at appl-ecosys.com> wrote: > > On Sat, 23 May 2015, Rob Willett wrote: > >> What I want to do is join the table Users and Perimeter Notifications >> together but only if the value of Devices.Holiday_Mode is either non >> existent or if Devices.Holiday_Mode does exist and its 0. If >> Devices.Holiday_Mode is 1 it means the user is on holiday and don?t send >> them anything. > > Rob, > > First, you can set holiday_mode to 0 by default rather than leaving it > NULL (unknown). As you wrote, unless the user explicitly sets the mode to 1 > the assumption is that its value is 0. After all, it's gotta' be one or the > other, right? > > Second, select * from Devices where holiday_mode == 0. Use that as a > sub-query and join users to the results. Now you have a list of user email > addresses for only those with holiday_mode of zero. > > HTH, > > Rich > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
