title: How to replace more than one character in oracle?
body: <p>How to replace multiple whole characters, except those in combinations...?</p>
  
  <p>The below code replaces multiple characters, but it also disturbing those in combinations.</p>
  
  <pre><code>SELECT regexp_replace('a,ca,va,ea,r,y,q,b,g','(a|y|q|g)','X') RESULT FROM dual;
  </code></pre>
  
  <p>Current output:</p>
  
  <pre><code>RESULT 
  --------------------
  X,cX,vX,eX,r,X,X,b,X
  </code></pre>
  
  <p>Expected output:</p>
  
  <pre><code>RESULT 
  ------------------------
  'X,ca,va,ea,r,X,X,b,X 
  </code></pre>
  
  <p>I just want to replace only separate whole characters('a','y','q','g'), but not the 1 in combinations('ca','va','ea')...</p>