title: Firebird constant value
body: <p>Is it possible to have database wide constants?
  What I want is to define a constant like:</p>
  
  <ul>
  <li>UPDATE_CONSTANT = 1 </li>
  <li>INSERT_CONSTANT = 2 </li>
  <li>DELETE_CONSTANT = 3</li>
  </ul>
  
  <p>and then use it  in for example a trigger like:</p>
  
  <pre class="lang-sql prettyprint-override"><code>CREATE TRIGGER AD_PRJ_PROJECTS FOR PRJ_PROJECT
  ACTIVE AFTER DELETE
  POSITION 1
  AS
  BEGIN
     EXECUTE PROCEDURE SP_ADD_HISTORY 'PRJ_PROJECT', DELETE_CONSTANT;
  END;
  </code></pre>