Get list of Dates based on conditions via SQL - mysql

Question

Currently having a little difficulty with respect to getting a list of dates.
I currently have the following SQL:
SELECT DISTINCT DATE(startDate) activity_date
, CASE WHEN (DATE(endDate) - DATE(startDate)) > 0 THEN DATE(endDate) ELSE FALSE END multiEvent
FROM activities
WHERE startdate BETWEEN '2017-08-01' AND '2017-08-31'
AND accountid = 578
ORDER
BY DATE(startdate)
Which gives the following result:
activity_date | multiEvent
2017-08-07 | 0
2017-08-07 | 2017-08-10
2017-08-18 | 0
However, what i am trying to achieve is, if multiEvent is not zero, then list the dates between the dates of activity_date & multiEvent into a single column.
Result I am trying to achieve:
activity_date |
2017-08-07 |
2017-08-07 |
2017-08-08 |
2017-08-09 |
2017-08-10 |
2017-08-18 |
ideas? :)

Answer 1

You need to first find a way to create rows for dates between activity_date and multiEvent. This query will produce the intended resultset of dates, as individual rows.
select date(eachDate) as eachDate from
(select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) as eachDate
from
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) as v
where
eachDate between date('2017-08-07')
and date('2017-08-10') order by eachDate asc ;
This will produce a result like
eachDate
2017-08-07
2017-08-08
2017-08-09
2017-08-10
Now, we need to fit in the above query with your existing query to get the intended output. The query would look something like this.
select
activity_date
from
(select
date(startDate) as activity_date
from
activities
where
startdate between date('2017-08-01') and date('2017-08-31')
and accountid = 578
and NOT (DATE(endDate) - DATE(startDate)) > 0
union all
select
eachDate
from
(select date(eachDate) as eachDate
from
(select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) as eachDate
from
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
(select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) as v
where
eachDate between date('2017-08-01')
and date('2017-08-31')) as dates_table
join
(select
date(startDate) as startDate,
date(endDate) as endDate
from
activities
where
startdate between date('2017-08-01') and date('2017-08-31')
and accountid = 578
and (date(endDate) - date(startDate)) > 0 ) as activities_table
on dates_table.eachDate between activities_table.startDate and activities_table.endDate) as main
order by
main.activity_date asc;
and the output looks like this.
activity_date
2017-08-07
2017-08-07
2017-08-08
2017-08-09
2017-08-10
2017-08-18