extra user attributes

Hi: I have freeradius working fine with users file in mysql instead of the "normal" users file (/etc/raddb/users). I need to have some custom user attributes for each user (lets call it custom1 and custom2 attributes and both are strings). Anybody knows what are the "best practices" to store those new custom attributes in the mysql tables? I am thinking simply to add more rows to the radcheck table having "username: user1, attribute: custom1, op:+=, value: val1". Thanks and best regards