Calculation in Time field

Question

Need to calculate values of A & B
Formula ->
A = Round down [A_TIME - A_STD]
B = Round up [A_TIME) - 10 minute + A_STD]
where
A_TIME     VARCHAR2(8)     N     Time           (Format“ HH:MM AM/PM”)      eg “3:50 PM”
A_STD     VARCHAR2(5)     N     Standard time      (Format“ HH:MM”)      eg “1:00”
Allowed values for A & B after round up/down = multiple of 10 ( 11:00,11:10,11:20 etc.)

Answer 1

Hi,
Welcome to the forum!
Whenever you have a question, please post a little sample data (CREATE TABLE and INSERT startements) and the results you want from that data.
Since this is your first messsage, I'll do it for you.
The sample data might be:
CREATE TABLE  table_x
(      a_time VARCHAR2 (8)
,      a_std  VARCHAR2 (5)
INSERT INTO table_x (a_time, a_std) VALUES ('3:50 PM', '1:00');
INSERT INTO table_x (a_time, a_std) VALUES ('3:50 AM', '-1:00');
INSERT INTO table_x (a_time, a_std) VALUES ('11:59 PM', '15');and the results you want from that data might be:
A_TIME   A_STD A        A
3:50 PM  1:00  02:50 PM 04:40 PM
3:50 AM  -1:00 04:50 AM 02:40 AM
11:59 PM 15    11:40 PM 12:10 AMOne way to get those results from that data (in Oracle 9 or higher) is:
WITH    got_nums     AS
     SELECT     a_time
     ,     a_std
     ,     24 * 60 * ( TO_DATE (a_time, 'HH:MI AM')
                      - TO_DATE ('01',   'DD')
                 )               AS t_minutes
     ,     (60 * NVL ( TO_NUMBER ( REGEXP_SUBSTR ( a_std
                                                  , '[-+]?[0-9]+:'
                          , '999D'
                                , 'NLS_NUMERIC_CHARACTERS = '' :'''
                 , 0
          ) + NVL ( TO_NUMBER ( REGEXP_SUBSTR ( a_std
                                                  , '[0-9]+$'
               , 0
               )               AS s_minutes
     FROM    table_x
SELECT       a_time
,       a_std
,       TO_CHAR ( TRUNC (SYSDATE) + ( TRUNC ( t_minutes - s_minutes
                                             , -1
                          / 24
                          / 60
            , 'HH:MI AM'
            )          AS a
,       TO_CHAR ( TRUNC (SYSDATE) + ( ( ROUND ( t_minutes + s_minutes - 5.01
                                                  , -1
                          / 24
                          / 60
            , 'HH:MI AM'
            )          AS a
FROM       got_nums
;This would probably be a lot simpler if you used different data types, perhaps a DATE or INTERVAL DAY TO SECOND for a_time, and either INTERVAL DAY TO SECOND or NUMBER for a_std. Explain what you're using these columns for. Are there other ways in which you need to manipulate these values?
Always say what version of Oracle you're using.