On 14 September 2016 at 12:20, Patrick B <patrickbakerbr@gmail.com> wrote: > I want to select all rows that have been modified from now to 4 months ago. > > I've used these queries: > >> select >> modified_date, >> from >> clients >> WHERE >> modified_date BETWEEN '2016-06-13' AND '2016-09-13' >
Going by my clock here 2016-06-13 was just over 3 months ago, not 4.
>> select >> modified_date, >> from >> clients >> WHERE >> modified_date >='2016-06-13' AND modified_date < '2016-09-13' > > > > But it didn't work... it returns 0 rows.... but there are rows to be shown: > > >> select modified_date from clients ORDER BY modified_date ASC > > > >> modified_date >> ------------------- >> 2015-07-11 17:23:40 >> 2016-09-13 20:00:51 >> 2016-09-13 20:00:51 >> 2016-09-13 20:00:51 >> 2016-09-13 20:00:51 > > > > What am I doing wrong?
None of those dates are between your specified date range. If you want to include all of 2016-09-13 timestamps, then you'd better do < '2016-09-14' since < '2016-09-13' will only cover timestamps on the 12th or before.
It didn't work before because, as excellently pointed out by Vitaly Burovoy, because
modified_date BETWEEN '2016-06-13' AND '2016-09-13'
is evaluated as
modified_date >= '2016-06-13 00:00:00' AND modified_date <= '2016-09-13 00:00:00'
None of your timestamps falls in that range. '2016-09-13 20:00:51' is 20 hours and 51 seconds after the end of this range, and '2015-07-11 17:23:40' is more than a year before it.
Similar logic applies to modified_date >= '2016-06-13 00:00:00' AND modified_date < '2016-09-13 00:00:00'
Now, the reason it is working for you now, is probably because you're in a timezone where it is already 2016-09-14, and your WHERE clause now reads:
modified_date >= '2016-06-14 00:00:00' AND modified_date < '2016-09-14 00:00:00'
with the effect that the timestamp '2016-09-13 20:00:51' now falls within the range of your new WHERE clause.