title: Update n random rows in SQL
body: <p>I have table which is having about 1000 rows.I have to update a column("X") in the table to 'Y' for n ramdom rows. For this i can have following query</p>
  
  <pre><code>update xyz set X='Y' when m in (
  'SELECT m FROM (SELECT m
  FROM xyz
  order by dbms_random.value
  ) RNDM 
  where rownum &lt; n+1);
  </code></pre>
  
  <p>Is there another efficient way to write this query. The table has no index.
  Please help?</p>