I had the same problem crossgrading. i had hundreds of users just 'disappear'.
I had them re-register and updated their post totals and reg date.
// Change post totals
UPDATE w3t_Users SET U_Totalposts='
###' WHERE U_Username='
username'
// Change registration date
UPDATE w3t_Users SET U_Registered=UNIX_TIMESTAMP('2002-12-25 12:00:00') WHERE U_Username='
username'
BUT
If you are going to upgrade to 6.2 BEWARE. The username is no longer part of the search processes, it's been changed to a posterid number instead.
So that means that any posts that were created by your 'lost users' before they re-registered, will now show as Anonymous (or blank) when you upgrade.
To avoid this, you will need to do a manual update for each user that re-registered.
First you will need to find out what the user number (
U_Number) is for your re-registered user in the w3t_users table.
Then you will do this query...
UPDATE w3t_Posts SET B_PosterID='
usernumber' WHERE B_Username='
username'
I'm still trying to figure out why those 'lost users' got lost in the first place. I've spent so many hours trying to fix the 'flawless conversion' <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
GOOD LUCK
