title: MYSQL UNION DISTINCT
body: <p>I have two selects that I'm currently running as a UNION successfully.</p>
  <pre><code>(SELECT a.user_id,
            a.updatecontents AS city,
            b.country
     FROM userprofiletemp AS a
     LEFT JOIN userattributes AS b ON a.user_id=b.user_id
     WHERE typeofupdate='city')
  UNION DISTINCT
    (SELECT a.user_id,
            c.city,
            c.country
     FROM userverify AS a
     LEFT JOIN userlogin AS b ON a.user_id=b.user_id
     LEFT JOIN userattributes AS c ON a.user_id=c.user_id
     WHERE b.active=1
       AND a.verifycity=0);
  </code></pre>
  <p>The results come back like this:</p>
  <pre><code>100 Melbourne Australia
  200 NewYork America
  300 Tokyo Japan
  100 Sydney Australia
  </code></pre>
  <p>The catch is the query will bring duplicate user_id (in this case the 100).
  The details in the first query take precedent for me and if the user_id is repeated in the second query I don't need it.</p>
  <p>Is there a way to get a UNION to be DISTINCT on a column? in this case the user_id?
  Is there a way to do the above call and not get duplicate user_id's - drop the second.
  Should I re-write the query differently and not use a UNION.
  Really want it as one query - I can use to SELECT's and PHP to weed out duplicate if necessary.</p>
  <p>thx
  Adam</p>