[Gio~Logist]

To make it remove just that secondary usergroup, try this:

UPDATE user
LEFT JOIN
        userfield on (user.userid = userfield.userid)
SET     user.membergroupids = TRIM(BOTH ',' FROM REPLACE(CONCAT(',', user.membergroupids, ','), ',SECONDARYUSERGROUPID,', ','))
WHERE   !FIND_IN_SET(userfield.fieldXXXX,'1,2,3')

To be sure that it works the way you want, make a test user that it would effect, then get that user's id and change

WHERE   !FIND_IN_SET(userfield.fieldXXXX,'1,2,3')

to

WHERE   !FIND_IN_SET(userfield.fieldXXXX,'1,2,3') AND user.userid = USERIDHERE

This way it will only effect that user and you can see if its working correctly :up: