[TYPO3] assigning usergroups to fe_users using SQL

[Panagiotis Kontaxis]

Hello list,

Sorry if you get multiple copies of this mail, but I have problems accepting
this mail by Mail Delivery System (I get Action: Failed, Diagnostic-Code:
X-Postfix; mail forwarding loop for  typo3-english at lists.netfielders.de)

I would like to change the usergroup of a fe user, using an sql query. If a
user is member of one group (with uid=2) I can do that with this query:
update fe_users set usergroup=2 where uid=.....

But how can assign a user to be a member in more than one usergroups with an
sql query?

thanks in advance!