Question

I have a table like this : (note that id_pack is not auto incremented)

id_pack       start_date         end_date           is_parent   id_contract
1             2011-11-01         2012-01-18         1           5547
2             2012-01-18         2050-01-01         1           5547
3             2009-02-02         2050-01-01         0           5547

where id_pack = 3 is the child of the two parents. I want to make a query to select the parents and the child for the month 2012-01 but the child needs to be doubled (because his first parent finished on 2012-01-18). So the result needs to look like this :

id_pack       start_date         end_date         id_parent
1             2012-01-01         2012-01-18       0
2             2012-01-18         2012-01-31       0
3             2012-01-01         2012-01-18       1
3             2012-01-18         2012-01-31       2

I have tried in every way and I can’t figure it out. I’m doing this because parents are assigned a price rate in another table, and for the current month the child had two parents with different price rates, so I need to charge from 2012-01-01 : 2012-01-18 using a rate plan and from 2012-01-18 : 2012-01-31 using another rate plan.

Is this even possible with one query ?

Thank you

PS: I have something like this :

    select c.id_pack,
            case when c.start_date < '2012-01-01' then '2012-01-01'
            else c.start_date
            end as start_date, 

            case end date ...... the same as start_date as end_date,


    from client a 
    join contract b on b.id_client = a.id_client
    join package c on c.id_contract = b.id_contract
       and c.start_date < dateadd(mm,1,'2012-01-01')
       and c.end_date >= '2012-01-01'
    where a.id_clinet = '12345'

Answer 1

Try:

select c.id_pack, p.start_date, p.end_date, coalesce(p.id_pack,0) id_parent
from package c
left join package p 
       on c.contract_id = p.contract_id and p.is_parent = 1 and c.is_parent = 0