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copied!<p>You can't sort on friend status because there is no friend status column. You can't do any complex SQL operations joining or unioning the <em>friends</em> table with another table because FQL doesn't support these operations. The best you can do is identify who the friends are via a separate query...</p> <pre><code>SELECT uid FROM friend WHERE uid IN (...ALL USER IDs...) </code></pre> <p>All the <em>uid</em>'s returned from that query will be a subset of your full list, including only those whom are friends.</p> <p><em><strong>Additional Info</em></strong>: </p> <p>The Meetup app is...</p> <ol> <li>First querying it's local database to generate a list of participants. (lets call the result [<code>participants</code>] )</li> <li><p>Then, they perform a query on the facebook <em>friend</em> database to determine which of those [<code>participants</code>] are friends. (lets call the result [<code>participating_friends</code>] )</p> <p><strong>SELECT uid FROM friend WHERE uid IN ([<code>participants</code>])</strong></p></li> <li><p>They also store that list of [<code>participating_friends</code>] uid's in their local database. One column is the user's id (<em>uid</em>) and the other is their friend's uid (<em>friendid</em>).</p></li> <li><p>Finally, to determine <em>friends of friends</em> they query their local friends database (from 3) with a query like:</p> <p><strong>SELECT <em>friendid</em> FROM local_friends WHERE <em>uid</em> IN ([<code>participating_friends</code>])</strong></p></li> </ol> <p><strong>UPDATE</strong>: In retrospect, Meetup might be casting an even wider net as follows:</p> <p>The Meetup app is...</p> <ol> <li>First querying it's local database to generate a list of participants. (lets call the result [<code>participants</code>] )</li> <li><p>Then, they perform a query on the facebook <em>friend</em> database to determine which of those [<code>participants</code>] are friends. (lets call the result [<code>participating_friends</code>] )</p> <p><strong>SELECT uid FROM friend WHERE uid IN ([<code>participants</code>])</strong></p></li> <li><p>Determining <strong>all</strong> friends of the app user who are also app users and store the result in a local database, saving <em>uid</em>'s and associated <em>friendid</em>'s.</p> <p><strong>SELECT uid FROM user WHERE uid IN (SELECT uid2 FROM friend WHERE uid1 = me()) AND is_app_user</strong></p></li> <li><p>Finally, to determine <em>friends of friends</em>, calculate the new set:</p> <p>[<code>participants_not_friends</code>] = [<code>participants</code>] - [<code>participating_friends</code>]. </p> <p>Then query the local friends database (from 3) with a query like:</p> <p><strong>SELECT <em>friendid</em> FROM local_friends WHERE <em>uid</em> IN ([<code>participants_not_friends</code>])</strong></p></li> </ol>

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