Voting System, database connections?

What you want are post meta/custom fields, using these functions:

• get_post_meta
• add_post_meta
• update_post_meta

Adding a new column to the posts table will only cause further issues down the line e.g.:

• database schema changes in WP Core destroying your extra column
• having to write your own custom SQL for everything related to post votes
• No help from WP_Query, object caches, and caching plugins
• No import/export support
• All post types will have the voting column, do you need voting data on attachments, post revisions, and pages?

E.g.

update_post_meta(76, 'my_key', 'Steve');

Will update/save a ‘my_key’ meta value of ‘steve’ to post 76, which we can then retrieve later on using:

echo get_post_meta( 76, 'my_key', true );

There is a similar meta API for users and comments