Renaming foreign-key columns in MySQL
AFAIK, dropping the constraint, then rename, then add the constraint back is the only way. Backup first!
In case anyone is looking for the syntax it goes something like this:
alter table customer_account drop foreign key `FK3FEDF2CC1CD51BAF`;
alter table customer_account add constraint `FK3FEDF2CCD115CB1A` foreign key (campaign_id) REFERENCES campaign(id);