title: Oracle Trigger update column in the same table
body: <p>I have table called <code>M_StockCode_JB</code> . Its fields are <code>Code</code>, <code>Description</code>, and <code>Display</code>.</p>
  
  <p>Display is still empty, but Code and Description has values as the following : </p>
  
  <pre><code>  M_StockCode_JB
  -----------------------
  Code    |   Description
  1       |   Apple
  2       |   Banana
  3       |   Pinneaple
  </code></pre>
  
  <p>I want to add column called 'Display' which contain both data from Code and Description, I plan to use this SQL <code>SELECT "NAME" ||'-' || DESCRIPTION FROM M_STOCKCODE_JB</code> so it will generated like this : </p>
  
  <pre><code>                M_StockCode_JB
      ------------------------------------------
      Code    |   Description    |   Display
      1       |   Apple          |   1-Apple
      2       |   Banana         |   2-Banana
      3       |   Pineapple      |   3-Pineapple
  </code></pre>
  
  <p>How can I insert to Display column as I add column Code and Description ? </p>