I need to create an inline view that will give me all dates between two
specified. Here is the question posed to me that I need to answer:
This basic query gets me the last 6 hours of history table entries for
an item, grouped into minutes (if an item has a delay of 5 seconds, it
takes the max out of each 11 entries per minutes).
set @iid=231;
set @hid=1;
select from_unixtime(t.clock), DATE_FORMAT(from_unixtime(t.clock),'%j
%h:%i %p') as mins, MAX(t.value) as value_max from history t where
t.itemid = (select itemid from items where itemid = @iid and hostid =
@hid) and DATE_SUB(CURRENT_TIMESTAMP(),INTERVAL 6 HOUR) <=
from_unixtime(t.clock) group by mins order by t.clock;
It'll fetch 360 entries (360 minutes in 6 hours) that looks like this:
from_unixtime(t.clock) mins value_max
2/24/2007 05:56:12 055 05:56 AM 0.29
2/24/2007 05:57:02 055 05:57 AM 0.2
2/24/2007 05:58:02 055 05:58 AM 0.23
2/24/2007 06:01:03 055 06:01 AM 0.02
2/24/2007 06:02:02 055 06:02 AM 0.08
The format you see for mins is DAY_OF_YEAR HOUR:MIN AM/PM. DAY_OF_YEAR
is unique, as in 55th day of this year.
Okay, so if I can JOIN this table with another table/view/sub query
that has EVERY MINUTE of the last 6 hours in a similarly formatted
column like 'mins', we should be able to spot the missing 2 minutes.
from_unixtime(t.clock) mins value_max
2/24/2007 05:56:12 055 05:56 AM 0.29
2/24/2007 05:57:02 055 05:57 AM 0.2
2/24/2007 05:58:02 055 05:58 AM 0.23
2/24/2007 05:59:02 055 05:59 AM NULL <<-- from the join
2/24/2007 06:00:02 055 06:00 AM NULL <<- from the join
2/24/2007 06:01:03 055 06:01 AM 0.02
2/24/2007 06:02:02 055 06:02 AM 0.08
Bryan Cantwell
Director, Development
(M) 469.361.1272
bcantwell@stripped
www.FireScope.net
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