title: Finding and removing Non-ASCII characters from an Oracle Varchar2
body: <p>We are currently migrating one of our oracle databases to UTF8 and we have found a few records that are near the 4000 byte varchar limit. 
  When we try and migrate these record they fail as they contain characters that become multibyte UF8 characters.
  What I want to do within PL/SQL is locate these characters to see what they are and then either change them or remove them.</p>
  
  <p>I would like to do :</p>
  
  <pre><code>SELECT REGEXP_REPLACE(COLUMN,'[^[:ascii:]],'')
  </code></pre>
  
  <p>but Oracle does not implement the [:ascii:] character class.</p>
  
  <p>Is there a simple way doing what I want to do?</p>