title: check if "it's a number" function in Oracle
body: <p>I'm trying to check if a value from a column in an oracle (10g) query is a number in order to compare it. Something like:</p>
  
  <pre><code>select case when ( is_number(myTable.id) and (myTable.id &gt;0) ) 
              then 'Is a number greater than 0' 
              else 'it is not a number' 
         end as valuetype  
    from table myTable
  </code></pre>
  
  <p>Any ideas on how to check that?</p>