Decoding and Converting VARCHAR Time in Oracle - oracle

Question

I need to query particular column in DB w/c is described as VARCHAR that I need to convert into Time Format (HH:MM) and then decode to its range value, to explain further... The column stores data when (time) a particular deal was made w/in the day and instead of returning the exact time it should return the time range it was done.
Col_1 is VARCHAR2(6)
select col_2, col_1 from table
Col_2 || Col_1
A || 9:56
B || 10:03
C || 21:53
My desired Output would be
Col_2 || Col_1
A || (09:00 - 10:00)
B || (10:00 - 11:00)
C || (2100 - 2200)
Really appreciate all your comments, as I'm stuck playing with this part for a couple of days now and its giving me nightmares, sorry I'm new to DB Oracle SQL stuff and still learning. :)

Answer 1

Like this?
In your output, 2100 - 2200 is not consistent with the rest; I ignored it.
What should happen when the input is like 10:00 even? That is in both 9:00-10:00 and in 10:00-11:00; I assumed you want the latter.
Finally, is 00:00 ok, or do you want that to be 24:00 instead (if it is at the end) - see the second example in my output.
with input_strings ( str ) as (
select '9:49' from dual union all
select '23:00' from dual
),
prep ( dt ) as (
select trunc(to_date(str, 'hh24:mi'),'hh') from input_strings
)
select to_char(dt, 'hh24:mi') || ' - ' || to_char(dt + 1/24, 'hh24:mi') as range
from prep;
RANGE
-------------
09:00 - 10:00
23:00 - 00:00

Answer 2

If you do to_date(col_1, 'HH24:MI') you'll get that tie on the first day of the month, as that what Oracle defaults to with no date specified. You can then truncate that to the hour, zeroing the minutes:
with t (col_2, col_1) as (
select 'A', '9:56' from dual
union all select 'B', '10:03' from dual
union all select 'C', '21:53' from dual
)
select col_2,
to_char(to_date(col_1, 'HH24:MI'), 'YYYY-MM-DD HH24:MI') as full_date,
to_char(trunc(to_date(col_1, 'HH24:MI'), 'HH24'), 'YYYY-MM-DD HH24:MI') as truncated
from t;
C FULL_DATE TRUNCATED
- ---------------- ----------------
A 2016-09-01 09:56 2016-09-01 09:00
B 2016-09-01 10:03 2016-09-01 10:00
C 2016-09-01 21:53 2016-09-01 21:00
That gives you the lower bound of your range. You can add an hour to the calculated date to get the upper limit, and then convert both back to string, and concatenate them together:
with t (col_2, col_1) as (
select 'A', '9:56' from dual
union all select 'B', '10:03' from dual
union all select 'C', '21:53' from dual
)
select col_2,
to_char(trunc(to_date(col_1, 'HH24:MI'), 'HH24'), 'HH24:MI') ||' - '||
to_char(trunc(to_date(col_1, 'HH24:MI') + 1/24, 'HH24'), 'HH24:MI')
from t;
C TO_CHAR(TRUNC
- -------------
A 09:00 - 10:00
B 10:00 - 11:00
C 21:00 - 22:00
You could also try to extract the hour value from your string and manipulate that, but then you have to manually deal with times between 23:00 and 00:00.
A third option is to use an interval instead of a date:
to_char(extract(hour from to_dsinterval('0 ' || col_1 || ':00')), 'FM00') ||':00 - '||
to_char(extract(hour from to_dsinterval('0 ' || col_1 || ':00')) + 1, 'FM00') ||':00'
but again this would show a time of say 23:15 as 23:00 - 24:00, so you'd need extra handling to show the upper bound as 00:00 in that case.