title: Simplest way to repeat every N rows in sql
body: <p>I know this is possible through some complex techniques, i want to know any simplest way to achieve this patter that every 10 rows should repeat .
  for example </p>
  
  <pre><code>        select a,b from tablename; (repeating 2 for example)
  </code></pre>
  
  <p>will give </p>
  
  <pre><code>        a1,b1     
          a2,b2
          a1,b1  
          a2.b2
          a3,b3
          a4,b4
          a3,b3
          a4,b4
  </code></pre>
  
  <p>where if it was 10 it will go like </p>
  
  <pre><code>    a1,b1 to a10,b10 again a1,b1 to a10,b10
  </code></pre>
  
  <p>then</p>
  
  <pre><code>    a11,b11 to a20,b20 again a11,b11 to a20,b20
  </code></pre>
  
  <p>and so on</p>