title: Change separator of WM_CONCAT function of Oracle 11gR2
body: <p>Normally, WM_CONCAT is an aggregate function that return values from table separated by comma like here.</p>
  
  <p>Suppose I have a table <code>foo</code> like this:</p>
  
  <pre><code>col_id     | col_text
  
  
  111        | This
  
  111        | is
  
  111        | a
  
  111        | test.
  </code></pre>
  
  <p>If I use this query:</p>
  
  <pre><code>SELECT CAST(WM_CONCAT(col_text) AS VARCHAR2(100)), col_id FROM foo
  </code></pre>
  
  <p>the result would be</p>
  
  <pre><code>This, is, a, test.
  </code></pre>
  
  <p>Is it possible to change the separator(<code>','</code>) to other characters like <code>'.'</code> or <code>'|'</code> of the <code>WM_CONCAT()</code> function?</p>
  
  <p>Or create a user defined function that can be executed like <code>WM_CONCAT()</code>?</p>