On Tue, Jan 21, 2003 at 08:43:29AM -0800, Josh L Bernardini wrote: > > I have three tables, people, events and epeople. epeople includes a person > id and an event id and works as a list of people attending events in the > database. > > The following query returns a list of all the people participating in a > particular event > given an event id. > > select people.id as pid, concat(lastname, ", ", firstname) as name from > events > left join epeople on events.id=epeople.eid > left join people on epeople.pid=people.id > where events.id=2; > > How could I get a list of all the people not participating? > thought I would add to the where clause with: > and people.id is null; > > but that returns an empty set.
Right. Presumably, there's no entry in your join table to link a person to an event that they're not attending. I've got a entry in the MySQL SQL section of my website called "Whether a row on one side of a many-to-many join is linked to a given row on the other side" that has a solution. http://users.starpower.net/rjhalljr/Serve Bob Hall --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
