title: What are RowMapper, ResultSetExtractor, bind variables and query types?
body: <p>I know how to use JDBC Template and DAO, but I still have questions regarding it:</p>
  
  <ol>
  <li>What's the use of <code>RowMapper</code> and <code>ResultSetExtractor</code>?</li>
  <li>What is a bind variable?</li>
  <li>Are queries a type of List?</li>
  </ol>