title: Oracle SQL - Find the MIN value of a dataset, but exclude a value in the MIN calculation
body: <p>Oracle version : 10g</p>
  
  <p>I'm trying to use the <code>MIN</code> function to find the minimum/lowest value of a dataset.  The column I'm performing <code>MIN</code> on is a <code>VARCHAR2</code> column.  This column will either contain a numeric value, or a value of '--' which represents that the value is not applicable.</p>
  
  <p>When performing the <code>MIN()</code> function on the column, the '--' is always returned.<br>
  I want to find a way to <em>exclude</em> the '--' from being calculated in the MIN statement.  I can't use the WHERE clause in the statement to filter out columns with a '--' because that would exclude valid data.</p>
  
  <p>Note:  This is a huge legacy query (500+ lines) so re-writing this massive query is not really an option.</p>