Below is what I am thinking, what it would do is make the webmaster (user 6 on your site) into user number 2. First, do you want the webmaster account to be changed into user 2? Second, I want some of the experts to check this below to make sure this looks right.
UPDATE w3t_Users
SET U_Number = '2'
WHERE U_Number = '6'
UPDATE w3t_Posts
SET B_PosterId = '2'
WHERE B_PosterId = '6'
UPDATE w3t_Messages
SET M_Uid = '2'
WHERE M_Uid = '6'
UPDATE w3t_Users
SET U_Totalposts = 'xxxxxx'
WHERE U_Number = '2'
