Need to give a user "superadmin" status through database
How can I promote another user to superuser status through the
  database?


There's only one "superuser" or root user in Drupal. That user has uid 1

Perhaps you need to update that user's password.

In D6, using just SQL, you can go

UPDATE users SET pass = MD5('password') WHERE uid = 1;


and then login with that username and password.

Note, make sure that's ok with the current uid 1 user, if it's not you.