Help needed with Left Join statements

[Chris Cox]

I am having a problem which may be a simple fix.

I have a table called Months, and contains only one column called mnth. It has integers 1 through 12.

I want to LEFT JOIN that table with two additional independent tables, so that I can show the count of records in the these tables for each month, and it will show zero if no records exist for any particular month. It works fine if I only join 1 additional table, but when I do it with two tables, the results are wrong.

I am using 3 tables (months, received, and sent).

Here is my example:


SELECT mnth,
COUNT(received.`timestamp`) AS received,
COUNT(sent.`timestamp`) AS sent

FROM months

LEFT JOIN received ON months.mnth= MONTH(received.`timestamp`)
AND received.user_id='1'
AND YEAR(received.`timestamp`)='2008'

LEFT JOIN sent ON months.mnth= MONTH(sent.`timestamp`)
AND sent.user_id='1'
AND YEAR(sent.`timestamp`)='2008'

GROUP BY mnth WITH ROLLUP