Oracle 9.2 Procedure to compare date and time separately [closed] - oracle

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I have the below logic to compare the date and time separately.
If current_date = DOG_Date and current time is less than 11.59pm
Set ARD date to current date + 1
Set ARD time to 08:00am
End if;
If current date greater than DOG Date and current time is less than 07.00am
Set ARD date to next Day (Can be same day)
Set ARD time to 08:00am
End if;
The ARD format should be dd.mm.yyyy
The ARD time should be 24hh.mi
Can you please help me with the PLSQL implementation of this? I tried and able to validate date part successfully, however finding problem with time part.
Thanks in advance,
Regards

Answer 1

There doesn't seem to be any benefit to splitting out the time and the date here. It seems to have obliged you to store both in character columns, which is a classic mistake - normally ending in disaster. Oracle's "date" data type is a datetime; it's worth using it.
Assuming all of your dates and times are actual dates you can simplify your logic considerably. Firstly "ARD Time" is 8am if any of your conditions are true. I suspect that your condition on 11.59pm is a mistake as well. If you mean less than midnight then this condition is always true and can be dispensed with. This in turn makes your logic for your first condition.
If the current date is equal to the DOG date then
ARD date is 8am tomorrow
This can be represented in PL/SQL as:
if trunc(sysdate) = trunc(dog_date) then
ard_date := trunc(sysdate) + interval '32' hour;
end if;
TRUNC(date) removes the time portion of a date by default. I know you're going to say that you want the date and the time separately, you can convert this date back to characters using TO_CHAR() in whatever manner you wish. Oracle includes datetime format models for time:
ard_date_char := to_char(ard_date, 'dd.mm.yyyy');
ard_time_char := to_char(ard_date, 'hh24:mi');
The mention of the "same" day in your second statement isn't as intuitive to strangers as you might expect. I assume it means here that your "day" starts at 7am.
To take your logic here bit-by-bit:
If current date greater than DOG Date
Can be represented as:
if trunc(sysdate) > trunc(dog_date)
and your second condition:
and current time is less than 07.00am
Is a comparison of the time on the current date against an arbitrary time. In order to do this comparison you can remove the time portion from the current date by using TRUNC() and then add 7 hours. By comparing this to the current system date you get your answer.
and sysdate < trunc(sysdate) + interval '7' hour
Now the difficult bit
Set ARD date to next Day (Can be same day)
Assuming (once again) that your "day" starts at 7am the increment required here could be anything from 1 minute to 24 hours. However, you already know that your current time is before 7am, which means that you are never in your "next" day. You can then always assume that it's the current day. This makes the complete logic:
if trunc(sysdate) > trunc(dog_date)
and sysdate < trunc(sysdate) + interval '7' hour
ard_date := trunc(sysdate) + interval '8' hour;
end if;
If your first IF statement really required 11.59pm you can use the same logic as in the second statement to do the comparison, i.e. trunc(sysdate) + 1 - interval '1' minute.
Although you haven't provided any code I suspect that the manner in which you're obtaining these dates would not preclude the placement in almost all of this logic in the creation of the date variable itself. Consider whether you actually need to do any of this and whether, for instance, a CASE statement when selecting the dates (if that is indeed what you're doing) would suffice.
Now, this all assumes you've actually used a date in order to store your dates. It doesn't sound like you have so you might have to convert everything to a date first and then back from a date afterwards. You do this using TO_DATE() and TO_CHAR().
I would highly recommend, though, that you convert everything to a date.

Answer 2

DECLARE
dog_date DATE := to_date( '20/11/2013','dd/mm/yyyy');
ard_date DATE;
BEGIN
IF TRUNC(CURRENT_DATE) = TRUNC(dog_date) AND CURRENT_DATE < TRUNC(CURRENT_DATE) + 1 THEN
ard_date := TRUNC(CURRENT_DATE) + 8/24 +1;
END IF;
IF TRUNC(CURRENT_DATE) > TRUNC(dog_date) AND CURRENT_DATE < TRUNC(CURRENT_DATE) + 7/24 THEN
ard_date := TRUNC(CURRENT_DATE) + 8/24 +1; --as your need
END IF;
END;