Question How can you produce a list of bookings on the day of 2012-09-14 which will cost the member (or guest) more than $30? Remember that guests have different costs to members (the listed costs are per half-hour 'slot'), and the guest user is always ID 0. Include in your output the name of the facility, the name of the member formatted as a single column, and the cost. Order by descending cost, and do not use any subqueries.
Answers and Discussion Show
select mems.firstname || ' ' || mems.surname as member,
facs.name as facility,
when mems.memid = 0 then
end as cost
inner join cd.bookings bks
on mems.memid = bks.memid
inner join cd.facilities facs
on bks.facid = facs.facid
bks.starttime >= '2012-09-14' and
bks.starttime < '2012-09-15' and (
(mems.memid = 0 and bks.slots*facs.guestcost > 30) or
(mems.memid != 0 and bks.slots*facs.membercost > 30)
order by cost desc;
This is a bit of a complicated one! While its more complex logic than we've used previously, there's not an awful lot to remark upon. The WHERE clause restricts our output to sufficiently costly rows on 2012-09-14, remembering to distinguish between guests and others. We then use a CASE statement in the column selections to output the correct cost for the member or guest.
As before, this answer requires multiple joins. It's more complex WHERE logic than you're used to, and will require a CASE statement in the column selections!
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