title: Regexp to catch string between first and second comma, where there's alphabetical character in number
body: <p>First, I must mention my native language is french, so I may make english mistake!</p>
  
  <p>I try to use sed to catch and delete the lines where the second item in a CSV file contains other characters then numbers.</p>
  
  <p>Here is an example of a OK line :</p>
  
  <pre><code>2323421,9781550431209,,2012-07-24 13:30:57,False,2012-07-01 00:00:00,False,118,,1,246501
  </code></pre>
  
  <p>A line that must be deleted :</p>
  
  <pre><code>1901461,3002CAN,,2010-09-29 13:46:59,True,,True,,,,
  </code></pre>
  
  <p>or</p>
  
  <pre><code>2977837,9782/76132396,,2015-04-27 10:14:47,True,2015-04-26 00:00:00,True,,,,
  </code></pre>
  
  <p>etc...</p>
  
  <p>I'm not sure this is possible to be honest!</p>
  
  <p>Thank you !</p>