My first thought was recursion - repeat the call for each element of the
result set, numbering each so you can find each level, until nothing is
returned. That would probably work, but oh, what a mess.
That triggered something ... off to consult Joe Celko's SQL for Smarties.
He has a whole chapter on Trees, and guess what: they're not easily done in
relational databases. To try and condense it here would be, shall we say,
impractical.
Check with a library, or try googling for trees -- hey, look what turned up:
http://www.dbmsmag.com/9603d06.html
by JC himself.
Have fun - Miles Thompson
At 03:19 PM 3/7/2006, Daevid Vincent wrote:
Thanks for the reply. However, that only gives me a single degree.
I'm looking for the way to traverse a 'tree' to see who is in your extended
networks, so I can do things like:
You are 4 degrees away from Sam:
You know bob who knows john who knows carrol who knows Sam.
Sam <- carrol <- john <- bob <- you
Etc.
> -----Original Message-----
> From: Micah Stevens [mailto:micah@xxxxxxxxxxxxxxxxxx]
> Sent: Monday, March 06, 2006 10:28 PM
> To: php-db@xxxxxxxxxxxxx
> Subject: Re: Help needed creating a social network
>
>
> CREATE TABLE `users` (userID int(11) not null auto_increment, primary
> key(userID), name tinytext not null, email tinytext not null);
>
> CREATE TABLE `links` (userID int(11), key (userID), friendID int(11),
> key(friendID));
>
> <?php
> $friends = mysql_query("select users.name, users.userID from
> users left join
> links on links.friendID = users.userID where links.userID =
> {$_GET['userID']}");
>
> echo "<h1>You have friends!!</h1>";
> while ($f = mysql_fetch_assoc($friends)) {
> echo "<a
> href='socialnetwork.php?userID={$f['userID']}'>{$f['name']}</a
> ><br>\n";
> }
>
> publish();
> profit($greatly);
> do (!$use) {
> coldfusion('Cause it sucks');
> }
> ?>
>
> (har har)
>
>
>
>
>
>
>
> On Monday 06 March 2006 9:47 pm, Daevid Vincent wrote:
> > Anyone have some pointers at a HowTo on creating a social network?
> >
> > Basically I need to show people in your immediate network,
> and also friends
> > of your friends, etc... Like the whole 'six degrees of
> separation' thing.
> > Ala: myspace, friendster, etc. ad nauseum.
> >
> > I prefer mySQL and PHP, but I could port from most any
> code. I guess I'm
> > mostly interested in the theory of this an how do I set up
> the tables
> > properly and what is the magic incantation (JOIN) to get
> this "chain" of
> > people.
>
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>
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