Question

Using the following sqlfiddle here How would I find the most recent payment made between the months of 2012-04-1 and 2012-03-31 using the case statement as in the previous queries
I tried this:

max(case when py.pay_date >= STR_TO_DATE(CONCAT(2012, '-04-01'),'%Y-%m-%d') and py.pay_date <=  STR_TO_DATE(CONCAT(2012, '-03-31'), '%Y-%m-%d') + interval 1 year  then py.amount end) CURRENT_PAY 

However the answer I am getting is incorrect, where the actual answer should be:(12, '2012-12-12', 20, 1)

Please Provide me with some assistance, thank you.

Answer 1

Rather than a CASE inside your MAX() aggregate, that condition belongs in the WHERE clause. This joins against a subquery which pulls the most recent payment per person_id by joining on MAX(pay_date), person_id.

SELECT payment.* 
FROM 
  payment
  JOIN (
    SELECT MAX(pay_date) AS pay_date, person_id 
    FROM payment 
    WHERE pay_date BETWEEN '2012-04-01' AND DATE_ADD('2012-03-31', INTERVAL 1 YEAR)
    GROUP BY person_id
  ) maxp ON payment.person_id = maxp.person_id AND payment.pay_date = maxp.pay_date
  

Here is an updated fiddle with the ids corrected in your table (since a bunch of them were 15). This returns record 18, for 2013-03-28.

Update

After seeing the correct SQL fiddle… To incorporate the results of this query into your existing one, you can LEFT JOIN against it as a subquery on p.id.

select p.name,
  v.v_name,
  sum(case when Month(py.pay_date) = 4 then py.amount end) april_amount,

   (case when max(py.pay_date)and month(py.pay_date)= 4 then py.amount else 0 end) max_pay_april,

   sum(case 
        when Month(py.pay_date) = Month(curdate())
        then py.amount end) current_month_amount,
   sum(case 
        when Month(py.pay_date) = Month(curdate())-1
        then py.amount end) previous_month_amount,
   maxp.pay_date AS last_pay_date,
   maxp.amount AS last_pay_amount
from persons p
left join vehicle v
  on p.id = v.person_veh
left join payment py
  on p.id = py.person_id
/* LEFT JOIN against the subquery: */
left join (
   SELECT MAX(pay_date) AS pay_date, amount, person_id 
      FROM payment 
      WHERE pay_date BETWEEN '2012-04-01' AND DATE_ADD('2012-03-31', INTERVAL 1 YEAR)
      GROUP BY person_id, amount
    ) maxp ON maxp.person_id = p.id

group by p.name,
  v.v_name