Group by multiple timestamps; join months but keep separate values - mysql

Question

I need to grab the # of settled and unsettled orders by month. Here is what I have so far:
SELECT
CONCAT(MONTH(time_settle), "/", YEAR(time_settle)) as month_settled, count(*) as settled
FROM payment_order
WHERE time_settle IS NOT NULL
AND datediff(time_settle,NOW())>-90
AND datediff(time_settle,NOW())<+90
AND account_id=28 AND current_state !="deleted"
GROUP BY MONTH(time_settle);
The result is:
month_settled | settled
-------------------------
6/2014 | 1
9/2014 | 10
12/2014 | 1
And unsettled I use time_due:
SELECT
CONCAT(MONTH(time_due), "/", YEAR(time_due)) as month_due, count(*) as unsettled
FROM payment_order
WHERE time_settle IS NULL
AND datediff(time_due,NOW())>-90
AND datediff(time_due,NOW())<+90
AND account_id=28
AND current_state !="deleted"
GROUP BY MONTH(time_due);
The result is:
month_due | unsettled
-------------------------
8/2014 | 1
9/2014 | 8
10/2014 | 2
I need a result that looks something like this:
month | settled | unsettled | total
----------------------------------------------
6/2014 | 1 | 0 | 1
8/2014 | 0 | 1 | 1
9/2014 | 10 | 8 | 18
10/2014 | 0 | 2 | 2
12/2014 | 1 | 0 | 1
Any ideas? How can I do a group by months if my sum criteria are two different months? I need the settled transactions to be grouped by time_settle and the unsettled transactions to be grouped by time_due.

Answer 1

Ok try this
SELECT t.month,
coalesce(t1.settled, 0) as settled,
coalesce(t2.unsettled, 0) as unsettled,
coalesce(t1.settled, 0) + coalesce(t2.unsettled, 0) as total
FROM
( SELECT CONCAT(MONTH(a.t_month), "/", YEAR(a.t_month)) as month
FROM
( SELECT COALESCE(time_settle, time_due) as t_month
FROM payment_order
)a
WHERE datediff(a.t_month,NOW())>-90 AND datediff(a.t_month,NOW())<+90
GROUP BY month
)t
LEFT JOIN(SELECT CONCAT(MONTH(time_settle), "/", YEAR(time_settle)) as month_settled, count(*) as settled FROM payment_order WHERE time_settle IS NOT NULL AND datediff(time_settle,NOW())>-90 AND datediff(time_settle,NOW())<+90 AND account_id=28 AND current_state !="deleted" GROUP BY EXTRACT(YEAR_MONTH FROM time_settle)) t1
on t1.month_settled = t.month
LEFT JOIN(SELECT CONCAT(MONTH(time_due), "/", YEAR(time_due)) as month_due, count(*) as unsettled FROM payment_order WHERE time_settle IS NULL AND account_id=28 AND current_state !="deleted" GROUP BY EXTRACT(YEAR_MONTH FROM time_due)) t2
on t2.month_due = t.month;
DEMO