Aggregate data from two tables with different field names I have two tables that each have date and amount fields.  This is for a donation system so one is pledges and the other is donations.  Here are the structure of relevant tables and fields:

pledges


pledge_date
amount_pledged


donations


processed_date
amount_donated


I would like to end up with results that sum pledges and donations by month.  Resulting in:  

Year    Month    Pledged    Donated
2015    01       120        80
2015    02       90         100
2015    05       0          10
2015    06       120        0


Obviously it's easy enough to get the data summed and grouped from the tables individually, but is there a way to get it all in one result set?  Here is the sample SQL to get the data just from the pledges table for example:

SELECT year(pledge_date) as year, month(pledge_date) as month, sum(amount_pledged) as pledged 
FROM pledges
GROUP by year(pledge_date), month(pledge_date)
ORDER by pledge_date ASC


I am trying to accomplish this in MySQL.  

Thanks to anyone for your help or clues on how to structure this!
SELECT year, month, sum(pledged) AS Pledged, sum(donated) AS DONATED FROM
(
SELECT year(pledge_date) as year, month(pledge_date) as month, amount_pledged  as pledged, 0 as donated FROM pledges
UNION
SELECT year(processed_date) as year, month(processed_date) as month, 0 as pledged, amount_donated as donated FROM **donations**
)x 
GROUP BY year, month 
ORDER BY year, month