SQL joins query not acting as wanted - sql

Question

I have the following tables:
CREATE TABLE `attendance_event_attendance` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`talk_id` varchar(200) NOT NULL,
`membersAttended_id` varchar(200) NOT NULL,
PRIMARY KEY (`id`),
KEY `attendance_event_attendance_9ace4e5a` (`talk_id`),
KEY `attendance_event_attendance_3c0dadb7` (`membersAttended_id`)
) ENGINE=MyISAM AUTO_INCREMENT=6 DEFAULT CHARSET=latin1;
CREATE TABLE `attendance_member` (
`name` varchar(200) NOT NULL,
`telephone_number` varchar(200) NOT NULL,
`email_address` varchar(200) NOT NULL,
`membership_type` varchar(1) NOT NULL,
`membership_number` varchar(200) NOT NULL,
PRIMARY KEY (`membership_number`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
CREATE TABLE `attendance_talk` (
`title` varchar(200) NOT NULL,
`speaker` varchar(200) NOT NULL,
`date_of_talk` date NOT NULL,
PRIMARY KEY (`title`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
I want to select all the members that have not attended the two latest talks. The query I have written looks like this:
SELECT m.name
from attendance_member as m
left outer join attendance_event_attendance as ea on (ea.membersAttended_id=m.membership_number)
join attendance_talk as t on (ea.talk_id = t.title)
where t.date_of_talk >= 2010-06-01
AND ea.membersAttended_id = null;
Is this correct? Or have I not understood joins correctly?

Answer 1

A somewhat horrible approach, I fear - but one that should work...
SELECT m.name
from attendance_member as m
left outer join (
SELECT ea.membersAttended_id
FROM attendance_event_attendance as ea
join attendance_talk as t on (ea.talk_id = t.title)
where t.date_of_talk >= 2010-06-01
GROUP BY ea.membersAttended_id
HAVING COUNT(*) = 2
) attendingmembers
ON attendingmembers.membersAttended_id = m.membership_number
WHERE attendingmembers.membersAttended_id IS NULL

Answer 2

Pretty much exactly like you would say it in English
Select Distinct m.name -- Select names
From attendance_member M -- of members
Where Not Exists -- who did not attend the last two talks
(Select * From attendance_event_attendance a
Join attendance_talk t
On a.talk_id = t.title
Where a.membersAttended_id = m.membership_number
And (Select Count(*) From attendance_talk
Where date_of_talk >= t. date_of_talk) <= 2)
NOTE: The subquery:
(Select * From attendance_event_attendance a
Join attendance_talk t
On a.talk_id = t.title
Where a.membersAttended_id = m.membership_number -- (correlated w/outer query)
And (Select Count(*) From attendance_talk
Where date_of_talk >= t. date_of_talk) <= 2)
returns the list of members who attended the talks which have 2 or fewer subsequent talks