Updating binary links

[Danny Lewkin]

Hello,

I have to 2 tables, tbl_usertypes and tbl_users. Between them there  
is a binary link, lnkusertype (so without objectpointers of foreign  
key).
I already have records in the tables, linked to eachother.
If I want to change the usertype of a user, it's clear to me that I  
have to change the link between that user in the tbl_user and the  
usertype in tbl_usertype.
But I can't seem to find any other way to do this, other than first  
unlink the existing link user-usertype, en linking it again.
Or is there another "update link" method in API or an "update link"  
SQL function, that I hav missed?

Thanks in advance,

Danny