Group Date column based on hours - sql

Question

I have a table in sqlite database where I store data about call logs. As an example assume that my table looks like this
| Calls_count | Calls_duration | Time_slice | Time_stamp |
| 10 | 500 | 21 | 1399369269 |
| 2 | 88 | 22 | 1399383668 |
Here
Calls_count is calls made since last observations
Calls_duration is the duration of calls in ms since last observations
Time-slice represents a time portion of week. Every day is divided into 4 portions of 6 hours each such that
06:00-11:59 | 12:00-17:59 | 18:00- 23.59 | 24:00-05:59 |
Mon| 11 | 12 | 13 | 14 |
Tue| 21 | 22 | 23 | 24 |
Wed| 31 | 32 | 33 | 34 |
Thu| 41 | 42 | 43 | 44 |
Fri| 51 | 52 | 53 | 54 |
Sat| 61 | 62 | 63 | 64 |
Sun| 71 | 72 | 73 | 74 |
And the time_stamp is unix epoch when the observation was made/ record was inserted in the database
Now I want to create a query so that if I specify time_stamp for a start and the end of week, The result is 168 rows of data, giving me sum of calls grouped by hour such that I get 24 rows for each day of week. This is an hourly break down of calls in a week.
SUM_CALLS | Time_Slice | Hour_of_Week |
10 | 11 | 1 |
0 | 11 | 2 |
....
7 | 74 | 167 |
4 | 74 | 168 |
In the above example of intended result,
1st row is Monday 06:00-06:59
2nd row is Monday 07:00-07:59
Last row is Sunday 04:00-05:59

Answer 1

Since version 3.8.3 SQLite supports common table expressions
and this is a possible solution
WITH RECURSIVE
hours(x,y) AS (SELECT CAST(STRFTIME('%s',STRFTIME('%Y-%m-%d %H:00:00', '2014-05-05 00:00:00')) AS INTEGER),
CAST(STRFTIME('%s',STRFTIME('%Y-%m-%d %H:59:59', '2014-05-05 00:00:00')) AS INTEGER)
UNION ALL
SELECT x+3600,y+3600 FROM hours LIMIT 168)
SELECT
COALESCE(SUM(Calls_count),0) AS SUM_CALLS,
CASE CAST(STRFTIME('%w',x,'unixepoch') AS INTEGER)
WHEN 0 THEN 7 ELSE STRFTIME('%w',x,'unixepoch') END
||
CASE
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '06:00:00' AND '11:59:59' THEN 1
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '12:00:00' AND '17:59:59' THEN 2
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '18:00:00' AND '23:59:59' THEN 3
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '00:00:00' AND '05:59:59' THEN 4
END AS Time_Slice,
((x-(SELECT MIN(x) FROM hours))/3600)+1 AS Hour_of_Week
FROM hours LEFT JOIN call_logs
ON call_logs.time_stamp >= hours.x AND call_logs.time_stamp <= hours.y
GROUP BY Hour_of_Week
ORDER BY Hour_of_Week
;
This is tested with SQLite version 3.7.13 without cte:
DROP VIEW IF EXISTS digit;
CREATE TEMPORARY VIEW digit AS SELECT 0 AS d UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
;
DROP VIEW IF EXISTS hours;
CREATE TEMPORARY VIEW hours AS SELECT STRFTIME('%s','2014-05-05 00:00:00') + s AS x,
STRFTIME('%s','2014-05-05 00:00:00') + s+3599 AS y
FROM (SELECT (a.d || b.d || c.d) * 3600 AS s FROM digit a, digit b, digit c LIMIT 168)
;
SELECT
COALESCE(SUM(Calls_count),0) AS SUM_CALLS,
CASE CAST(STRFTIME('%w',x,'unixepoch') AS INTEGER)
WHEN 0 THEN 7 ELSE STRFTIME('%w',x,'unixepoch') END
||
CASE
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '06:00:00' AND '11:59:59' THEN 1
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '12:00:00' AND '17:59:59' THEN 2
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '18:00:00' AND '23:59:59' THEN 3
WHEN STRFTIME('%H:%M:%S',x,'unixepoch') BETWEEN '00:00:00' AND '05:59:59' THEN 4
END AS Time_Slice,
((x-(SELECT MIN(x) FROM hours))/3600)+1 AS Hour_of_Week
FROM hours LEFT JOIN call_logs
ON call_logs.time_stamp >= hours.x AND call_logs.time_stamp <= hours.y
GROUP BY Hour_of_Week
ORDER BY Hour_of_Week
;