Select Distinct Rows Outside of Time Frame - sql

Question

I am trying to use SQL to select distinct data entries based on the time difference between one entry and the next. It's easier to explain with an example:
My data table has
Part DateTime
123 12:00:00
123 12:00:05
123 12:00:06
456 12:10:23
789 12:12:13
123 12:14:32
I would like to return all rows as long with the limitation that if there are multiple entries with the same "Part" number I would like to retrieve only those that have a difference of at least 5 minutes.
The query should return:
Part DateTime
123 12:00:00
456 12:10:23
789 12:12:13
123 12:14:32
The code I'm using is the following:
SELECT data1.*, to_char(data1.scan_time, 'yyyymmdd hh24:mi:ss')
FROM data data1
where exists
(
select *
from data data2
where data1.part_serial_number = data2.part_serial_number AND
data2.scan_time + 5/1440 >= data1.scan_time
and data2.info is null
)
order by to_char(data1.scan_time, 'yyyymmdd hh24:mi:ss'), data1.part_serial_number
This is not working unfortunately. Does anyone know what i'm doing wrong or can suggest an alternate approach??
Thanks

Answer 1

Analytic functions to the rescue.
You can use the analytic function LEAD to get the data for the next row for the part.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 123 part, timestamp '2011-12-08 00:00:00' ts
3 from dual
4 union all
5 select 123, timestamp '2011-12-08 00:00:05'
6 from dual
7 union all
8 select 123, timestamp '2011-12-08 00:00:06'
9 from dual
10 union all
11 select 456, timestamp '2011-12-08 00:10:23'
12 from dual
13 union all
14 select 789, timestamp '2011-12-08 00:12:13'
15 from dual
16 union all
17 select 123, timestamp '2011-12-08 00:14:32'
18 from dual
19 )
20 select part,
21 ts,
22 lead(ts) over (partition by part order by ts) next_ts
23* from x
SQL> /
PART TS NEXT_TS
---------- ------------------------------- -------------------------------
123 08-DEC-11 12.00.00.000000000 AM 08-DEC-11 12.00.05.000000000 AM
123 08-DEC-11 12.00.05.000000000 AM 08-DEC-11 12.00.06.000000000 AM
123 08-DEC-11 12.00.06.000000000 AM 08-DEC-11 12.14.32.000000000 AM
123 08-DEC-11 12.14.32.000000000 AM
456 08-DEC-11 12.10.23.000000000 AM
789 08-DEC-11 12.12.13.000000000 AM
6 rows selected.
Once you've done that, then you can create an inline view and simply select those rows where the next date is more than 5 minutes after the current date.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 123 part, timestamp '2011-12-08 00:00:00' ts
3 from dual
4 union all
5 select 123, timestamp '2011-12-08 00:00:05'
6 from dual
7 union all
8 select 123, timestamp '2011-12-08 00:00:06'
9 from dual
10 union all
11 select 456, timestamp '2011-12-08 00:10:23'
12 from dual
13 union all
14 select 789, timestamp '2011-12-08 00:12:13'
15 from dual
16 union all
17 select 123, timestamp '2011-12-08 00:14:32'
18 from dual
19 )
20 select part,
21 ts
22 from (
23 select part,
24 ts,
25 lead(ts) over (partition by part order by ts) next_ts
26 from x )
27 where next_ts is null
28* or next_ts > ts + interval '5' minute
SQL> /
PART TS
---------- -------------------------------
123 08-DEC-11 12.00.06.000000000 AM
123 08-DEC-11 12.14.32.000000000 AM
456 08-DEC-11 12.10.23.000000000 AM
789 08-DEC-11 12.12.13.000000000 AM

Answer 2

AFJ,
let's supose that we have a new field that tell us if exists a previus entry for this Part in the previous 5 minutes, then, taking the rows that this field is set to False we have the result.
select
Part,
DateTime,
coalesce(
(select distinct 1
from data ds
where ds.Part = d.Part
and ds.DateTime between d.DateTime and d.DateTime - 5/1440
)
, 0) as exists_previous
from data d
The subquery checks if they are a row with same Part in previous 5 minutes inteval
Result must be:
Part DateTime exists_previous
123 12:00:00 0
123 12:00:05 1
123 12:00:06 1
456 12:10:23 0
789 12:12:13 0
123 12:14:32 0
now, filter to get only rows with 0:
select Part, DateTime from
(select
Part,
DateTime,
coalesce(
(select distinct 1
from data ds
where ds.Part = d.Part
and ds.DateTime between d.DateTime and d.DateTime - 5/1440
)
, 0) as exists_previous
from data D
) T where T.exists_previous = 0
Disclaimer: not tested.

Answer 3

This has not been verified, but essentially, the trick is to group by part AND time divided by 5 minutes (floored).
select part, min(scan_time)
from data
group by part, floor(scan_time/(5/1440))
order by scan_time;