title: how to define composite primary key in mybatis mapping
body: <p>I have a table called <strong>post_locations(post_id,location_id,location_name,created_ts,updated_ts,created_by,updated_by)</strong> with composite primary key on two columns <strong>post_id,location_id</strong>. I tried defining id property on both the column but  couldn't succeed.</p>
  
  <p>i did not find any documentation on this topic please help me solving this issue </p>