title: Oracle REGEXP to replace only the first character
body: <p>In the example below:</p>
  
  <pre><code>WITH X(DATA, ORD)
  AS
  (         
  Select '@asdf@'   , 01 FROM DUAL UNION
  Select '\qw@er\'  , 02 FROM DUAL UNION
  Select '-zxcv-@' , 03  FROM DUAL UNION
  Select '_poiu@' ,  04 FROM DUAL 
  )
  
  SELECT
  REGEXP_REPLACE(DATA, '[@\-_]', '', 1)
  FROM X
  ORDER BY ORD;  
  ;  
  </code></pre>
  
  <p>I get this response:</p>
  
  <pre><code>asdf 
  qwer
  -zxcv- 
  poiu
  </code></pre>
  
  <p>But I would like to replace the "@", or the "\" or the "-" or the "_" only if it is the first character on the string, not in the middle.
  Plus it is not working for the "-" character.</p>