Subtracting/Adding to a Where clause timestamp condition - oracle

Question

I'm attempting to speed up a timestamp comparison query by restricting the query to 30 minutes before and after the timestamp in question. This is the format I'm using:
Causedat
-----
11-NOV-15 10.20.58.000000000 AM
11-NOV-15 10.19.41.877000000 AM
10-NOV-15 11.01.40.000000000 AM
10-NOV-15 11.00.50.460000000 AM
05-NOV-15 01.53.30.966000000 PM
05-NOV-15 01.47.31.000000000 PM
What I'm trying to do is write a condition where i'll tell the system only to look for dates in the system that are +-00:30:00.000000000 (thirty minutes) from the Causedat date in the future or past from that time.
I've seen that for example, SYSDATE - SYSTIMESTAMP is a legitimate calculation. Is it possible to do something similar to this like this:
WHERE search.date >= (Causedat = Causedat - '000000000 00:30:00.000000000')
AND search.date <= (Causedat = Causedat + '000000000 00:30:00.000000000')
Please assume the date i'm searching and Causedat are in the same (timestamp) format for this question.
Thank you for any light you may be able to shine on the problem for me.

Answer 1

You can add an interval to a timestamp; you can read about datetime and interval arithmetic. There are conversion functions to go from a variable to an interval, but with known fixed values you can use an interval literal here. You can use the full string you have:
where search_date >= causedat - interval '000000000 00:30:00.000000000' day to second
and search_date <= causedat + interval '000000000 00:30:00.000000000' day to second;
Or just the non-zero part:
where search_date >= causedat - interval '30' minute
and search_date <= causedat + interval '30' minute;
Trivial demo of how these evaluate:
select systimestamp,
systimestamp - interval '000000000 00:30:00.000000000' day to second as minus_30,
systimestamp + interval '000000000 00:30:00.000000000' day to second as plus_30
from dual;
SYSTIMESTAMP MINUS_30 PLUS_30
----------------------------------- ----------------------------------- -----------------------------------
18-NOV-15 11.39.09.597473000 +00:00 18-NOV-15 11.09.09.597473000 +00:00 18-NOV-15 12.09.09.597473000 +00:00
select systimestamp,
systimestamp - interval '30' minute as minus_30,
systimestamp + interval '30' minute as plus_30
from dual;
SYSTIMESTAMP MINUS_30 PLUS_30
----------------------------------- ----------------------------------- -----------------------------------
18-NOV-15 11.39.09.653809000 +00:00 18-NOV-15 11.09.09.653809000 +00:00 18-NOV-15 12.09.09.653809000 +00:00

Answer 2

Direct arithmetic on date time column with required interval value.
WHERE search.date
BETWEEN Causedat - INTERVAL '30' MINUTE
AND Causedat + INTERVAL '30' MINUTE

Answer 3

I just went through the question. I have provided a simple example to illustrate how we can achieve this.
SELECT A.DT
FROM
( SELECT SYSTIMESTAMP - INTERVAL '60' MINUTE AS DT FROM DUAL
UNION
SELECT SYSTIMESTAMP - INTERVAL '30' MINUTE AS DT FROM DUAL
UNION
SELECT SYSTIMESTAMP AS DT FROM DUAL
UNION
SELECT SYSTIMESTAMP + INTERVAL '30' MINUTE AS DT FROM DUAL
UNION
SELECT SYSTIMESTAMP + INTERVAL '60' MINUTE AS DT FROM DUAL
)A
WHERE A.DT BETWEEN (SYSTIMESTAMP - INTERVAL '30' MINUTE) AND (SYSTIMESTAMP + INTERVAL '30' MINUTE);
Let me know if this helps.