Dynamic due dates checking with the given period of dates - mysql

Question

id start_date interval period
1 1/22/2018 2 month
2 2/25/2018 3 week
3 11/24/2017 3 day
4 7/22/2017 1 year
5 2/25/2018 2 week
the above is my table data sample. start_dates will be expired based on interval and period(i.e id-1 will have due date after 2 months from the start_date, id-2 will have due after 3 weeks vice versa). period is enum of (day,week,month,year). Client can give any period of dates. let's say 25-06-2026 to 13-07-2026 like that.. I have to return the ids whose due dates falls under that period.I hope i made my question clear.
Here what i have done to resolve this. I am using mysql 5.7. I found ways to achieve this with recursive CTE's.(not available in mysql 5.7). and there is a way to achieve this by populating virtual records by using inline sub queries along with unions and its a performance killer and there is restriction of population of records.(like given in the link Generating a series of dates) I have reached a point to get results for a single date which is very easy. Below is my query(in oracle)
select id
from (select a.*,
case
when period='week'
then mod((to_date('22-07-2018','dd-mm-yyyy')-start_date),7*interval)
when period='month' and to_char(to_date('22-07-2018','dd-mm-yyyy'),'dd')=to_char(start_date,'dd')
and mod(months_between(to_date('22-07-2018','dd-mm-yyyy'),start_date),interval)=0
then 0
when period='year' and to_char(to_date('22-07-2018','dd-mm-yyyy'),'dd-mm')=to_char(start_date,'dd-mm')
and mod(months_between(to_date('22-07-2018','dd-mm-yyyy'),start_date)/12,interval)=0
then 0
when period='day'
and mod((to_date('22-07-2018','dd-mm-yyyy')-start_date),interval)=0
then 0 else 1 end filter from kml_subs a)
where filter=0;
But I need to do this for a period of dates not a single date. Any suggestions or solutions will be much appreciated.
Thanks,
Kannan

Answer 1

Assuming this is an Oracle question and not MySQL:
I think the first thing that you need to do is calculate when the due date is. I think a simple case statement can handle that for you:
case when period = 'day' then start_date + numtodsinterval(interval,period)
when period = 'week' then start_date + numtodsinterval(interval*7,'day')
when period = 'month' then add_months(start_date,interval)
when period = 'year' then add_months(start_date,interval*12)
end due_date
Then, using that new due_date field, you can check if the due date falls between the desired date range.
select *
from(
select id,
start_date,
interval,
period,
case when period = 'day' then start_date + numtodsinterval(interval,period)
when period = 'week' then start_date + numtodsinterval(interval*7,'day')
when period = 'month' then add_months(start_date,interval)
when period = 'year' then add_months(start_date,interval*12)
else null end due_date
from data)
where due_date between date '2018-02-25' and date '2018-03-12'
The above query checking between 2/25/18 and 3/12/18 produces the following output using your data:
+----+-------------+----------+--------+-------------+
| id | start_date | interval | period | due_date |
+----+-------------+----------+--------+-------------+
| 2 | 05-FEB-2018 | 3 | week | 26-FEB-2018 |
| 5 | 25-FEB-2018 | 2 | week | 11-MAR-2018 |
+----+-------------+----------+--------+-------------+