;; Make a string like DATETIME(DATE('now', 'start of month'), '-1 month')
;; The date bucketing will end up being done twice since `date` is called on the results of `date-interval` automatically. This shouldn't be a big deal because it's used for relative dates and only needs to be done once in a given query.
;; The date bucketing will end up being done twice since `date` is called on the results of `date-interval` automatically. This shouldn't be a big deal because it's used for relative dates and only needs to be done once.
;; It's important to call `date` on 'now' to apply bucketing *before* adding/subtracting dates to handle certain edge cases as discussed in issue #2275 (https://github.com/metabase/metabase/issues/2275).
;; Basically, March 30th minus one month becomes Feb 30th in SQLite, which becomes March 2nd. DATE(DATETIME('2016-03-30', '-1 month'), 'start of month') is thus March 1st.
;; The SQL we produce instead (for "last month") ends up looking something like: DATE(DATETIME(DATE('2015-03-30', 'start of month'), '-1 month'), 'start of month'). It's a little verbose, but gives us the correct answer (Feb 1st).
