tom@gmail.com   webapp4     webapps
tom@gmail.com   webapp6     webapps
tom@gmail.com   mswin3      windows
tom@gmail.com   mswin2      windows
sakur@gmail.com mswin2      windows
sakur@gmail.com webapp6     webapps

SELECT *
  FROM (  SELECT    'SYNC rss_user WITH rss_user_name = "'
             || RSS_USER_NAME
             || '" , rss_name = "'
             || RSS_NAME
             || '" , rss_type = "'
             || RSS_TYPE
             || '";'
        FROM rss_user
    ORDER BY DBMS_RANDOM.VALUE)
 WHERE ROWNUM = 1

SYNC rss_user WITH rss_user_name = "tom@gmail.com" , rss_name = "webapp4" , rss_type = "webapps";

SELECT *
  FROM (SELECT    'SYNC rss_user WITH rss_user_name = "'
             || RSS_USER_NAME
             || '" , rss_name = "'
             || RSS_NAME
             || '" , rss_type = "'
             || RSS_TYPE
             || '";',
                 seqnum = row_number() over (partition by rss_name, rss_type order by dbms_random.value)
         FROM rss_user
        ) t
 WHERE seqnum = 1

select rss_name, rss_type, max(rand) from
(select rss_name, rss_type, <random number> as rand from rss_user) a
group by rss_name, rss_type