title: Get substring into a new column
body: <p>I have a table that contains a column that has data in the following format - lets call the column "title" and the table "s"</p>
  
  <p>title</p>
  
  <pre><code>ab.123
  ab.321 
  cde.456
  cde.654
  fghi.789
  fghi.987
  </code></pre>
  
  <p>I am trying to get a unique list of the characters that come before the "." so that i end up with this:</p>
  
  <pre><code>ab
  cde
  fghi
  </code></pre>
  
  <p>I have tried selecting the initial column into a table then trying to do an update to create a new column that is the position of the dot using "ss".</p>
  
  <p>something like this:</p>
  
  <pre><code>t: select title from s
  update thedot: (title ss `.)[0] from t
  </code></pre>
  
  <p>i was then going to try and do a 3rd column that would be "N" number of characters from "title" where N is the value stored in "thedot" column.</p>
  
  <p>All i get when i try the update is a "type" error.</p>
  
  <p>Any ideas? I am very new to kdb so no doubt doing something simple in a very silly way.</p>