title: How can I make SQL Developer/SQL+ prompt only once for a substitution variable that occurs multiple times in a single statement?
body: <p>I have a query roughly like this:</p>
  
  <pre><code> select * 
    from A_TABLE 
    where A_COLUMN = '&amp;aVariable'
      union
   select * 
    from A_TABLE 
    where B_COLUMN = '&amp;aVariable';
  </code></pre>
  
  <p>But when I run it, SQL Developer prompts me for the variable twice, even though it's the same variable.</p>
  
  <p>If there's a way to make it prompt only once for a variable that is used twice, how do I do it?</p>
  
  <p>I do <strong>not</strong> want to use a script, it must be a single executable query.</p>