title: REGEXP_REPLACE replacing text with the same text in lower case
body: <p>I am trying to use <code>REGEXP_REPLACE</code> in PL/SQL to replace some text with the same text in lower case. Actually, the rule is that I want all text between <code>"()"</code> that has only one char to be in lower case.</p>
  
  <p>Here is an example :</p>
  
  <pre><code>SELECT REGEXP_REPLACE(
    'i want what what is between &lt;&gt; in lower case : I am a test(E) (A) (HELLO)'
    , '(\(\D\))', '&lt;\1&gt;'
  ) FROM DUAL
  </code></pre>
  
  <h2>Result :</h2>
  
  <pre><code>I want what is between &lt;&gt; in lower case : I am a test(e) (a) (HELLO)
  </code></pre>
  
  <p>or this because I am a little confuse about my exercice:</p>
  
  <pre><code>I want what is between &lt;&gt; in lower case : I am a test&lt;(e)&gt; &lt;(a)&gt; (HELLO)
  </code></pre>
  
  <p>How can I get my text in lower case ? I tried in several ways but I can't get out with it. I don't know hot to tell <code>REGEXP_REPLACE</code> to put <code>"\1"</code> content in lower case.</p>
  
  <p>Thanks you for your help.</p>
  
  <p>Best regards.
  MS</p>