title: Get certain number of characters after a delimiter in postgres
body: <p>I need to extract certain number of characters from the detailed string field in db table.</p>
  
  <p>sub_str will not work because it ask for position and in this case position is different in every row.</p>
  
  <p>split_part will not work as it will return the complete part after delimiter and we just need 6 characters</p>
  
  <p>Example of values            :                                           Expected Result:</p>
  
  <pre><code>461/5-6 srj pt no 101 B up ml to dn ml                      101 B   
  461/5-6 srj pt no107A up ml to up loop line                 107A
  461/5-6 srj pt no 102 A dn ml to dn loop line               102 A
  461/6-7 srj pt no 107 B up loop line up ml                  107 B
  461/6-7 gf 10 dn loop to dead end                           10
  461/7-8 srj of ds gf 13 B machine siding to up loop line    13 B
  461/7-8 srj gf 10A machine siding to dn loop line           10A
  </code></pre>
  
  <p>and so on.</p>