title: REGEXP_REPLACE - remove commas from string ONLY if enclosed in ()'s
body: <p>I find an example at oracle forum site :</p>
  
  <p>Input string : <code>a, b, c (x, y, z), a, (xx, yy, zz), x,</code></p>
  
  <pre><code>WITH t AS (SELECT 'a, b, c (x, y, z), a, (xx, yy, zz), x,' col1 
           FROM dual)
  SELECT t.col1
   , REGEXP_REPLACE(t.col1, '(\(.*?\))|,', '\1') new_col
  FROM t
  </code></pre>
  
  <p>Output : <code>a b c (x, y, z) a (xx, yy, zz) x</code></p>
  
  <p>But i want to make opposite of that. Just remove this character <code>,</code> from inside <code>()</code> and remain outside.</p>
  
  <p>Output : <code>a, b, c (x y z), a, (xx yy zz), x,</code></p>