I am sorry, but we don't support direct database manipulation.
Having said that, which setting exactly are you trying to update? There is the "Add Comments" setting and also the "Who Can Send You Messages" setting. I assume you want both of those to default to everyone.
The second one is the easiest. On the Settings page of the control panel, in the Messaging section, there is a User Default Availability dropdown that you can set to Everyone. For existing users you may need to run a script to update them all, or just let them do it themselves.
For the first one, comments, please see this topic:
http://www.activemodules.com/active...t-working/ It does default to Friends now though.