title: Create custom column in post table in wordpress
body: <p>I want to add two custom field to table <code>wp_posts</code>, and that I need for my plugin.
  now to enable these fields I have changed core file of wordpress </p>
  
  <pre><code>wordpress/wp-admin/post.php
  $data = compact( array( 'post_author', 'post_date', 'post_date_gmt', 'post_content', 'post_content_filtered', 'post_title', 'post_excerpt', 'post_status', 'post_type', 'comment_status', 'ping_status', 'post_password', 'post_name', 'to_ping', 'pinged', 'post_modified', 'post_modified_gmt', 'post_parent', 'menu_order', 'post_mime_type', 'guid' ) );
  </code></pre>
  
  <p>here I have added two fields which I want.</p>
  
  <p>Now I want these things as installable( I have manually added two fields here). </p>
  
  <p>So how to do that within plugin.</p>
  
  <p>I have read one post </p>
  
  <pre><code>http://wp.tutsplus.com/tutorials/creative-coding/add-a-custom-column-in-posts-and-custom-post-types-admin-screen/
  </code></pre>
  
  <p>here hooks are used in theme function.php,but i want to do in plugin itself.</p>
  
  <p>I am using wordpress 3.6.</p>
  
  <p>still any confusion please comment I will update.</p>