Question

Im having a mysql problem, I am trying to find the most current value for a specific month, the entire table schema and data can be seen here, the query that I have written to accomplish this is as follows:

max(case 
when Month(py.pay_date) = 8
then amount  end) previous_month_amount

However It is not returning the correct values, in this case the correct values should be:

name  previous_month_amount
Carl      30
Mark      40

Hope I made the question clear enough, and thank you for your help.

Answer 1

I am interpreting your question as “What is the last payment made in each month?” If you answer this, then you can get the appropriate “last payment” just by choosing the right month. The following query does this:

select p.name, lp.yr, lp.mon, pa.amount
from persons p join
     (select person_id, year(pay_date) as yr, month(pay_date) as mon,
             max(pay_date) as max_pay_date
      from payment
      group by person_id, year(pay_date), month(pay_date)
     ) lp
     on p.id = lp.person_id join
     payment pa
     on p.id = pa.person_id and
        pa.pay_date = lp.max_pay_date
group by p.name, lp.yr, lp.mon, pa.amount