title: getting error while trying to extract month from date
body: <p>I want to extract month from input date. I am trying this</p>
  
  <pre><code>select
      case
          when extract(month from :myDate) &lt;= 6 then '1st' 
          when extract(month from :myDate) &gt;= 7 then '2nd'
      end as half_of_the_year
  from dual
  </code></pre>
  
  <p>If i enter <code>2-12-12</code> then i get the error that</p>
  
  <pre><code>ORA-30076: invalid extract field for extract source
  30076. 00000 -  "invalid extract field for extract source"
  *Cause:    The extract source does not contain the specified extract field.
  *Action:
  </code></pre>
  
  <p>Why i am getting this error ?</p>
  
  <p>Thanks</p>