title: performance difference between to_char and to_date
body: <p>I have simple SQL query.. on Oracle 10g. I want to know the difference between these queries: </p>
  
  <pre><code>select * from employee where id = 123 and 
            to_char(start_date, 'yyyyMMdd') &gt;= '2013101' and 
            to_char(end_date, 'yyyyMMdd') &lt;= '20121231';
  
  select * from employee where id = 123 and 
            start_date &gt;= to_date('2013101', 'yyyyMMdd') and 
            end_date &lt;= to_date('20121231', 'yyyyMMdd');
  </code></pre>
  
  <p>Questions: 
  1. Are these queries the same? start_date, end_date are indexed date columns. 
  2. Does one work better over the other? </p>
  
  <p>Please let me know. thanks. </p>