If you're running 7.3, then what you could do is use the Content Rebuilder section, and rebuild the post content. This will take what is in the POST_DEFAULT_BODY and then populate the POST_BODY field.
If your POST_DEFAULT_BODY already contains all of the marked up code and could be used directly, another option is just to run a simple query and set the POST_BODY to be the same as POST_DEFAULT_BODY
update ubbt_POSTS set POST_BODY = POST_DEFAULT_BODY
