find_or_create_by updating id

I'm working on a RoR projects. I'm migrating a user table. Because the new dbase has a different set up and I want to seperate the login stuff from the personal/settings stuff I'm not importing the dbase; I migrate all attribute separately. I want to keep the old user id's. When I use user=User.new I can do user.id = migratee.user_id and I keep the same user_id. Unfortunately in the old table different users where registered with the same email address (don't ask why). Off course I don't want that so what I do in stead of user=User.new is user=User.find_or_create_by_email(migratee.email). This is going to l开发者_StackOverflow中文版ead to some problems, I know, since users with same email address will be overwritten. This is a problem I 'll deal with seperately. My problem is that when I do user.id = migratee.user_id after user=User.find_or_create_by_email(migratee.email) the old ID isn't migrated but a new auto-incrementing id is assigned. Anybody know how to avoid that?

Regards,

Rutger

I don't know how your query looks like. If you're doing an INSERT SELECT you can add a HAVING to filter existing email adresses. Otherwise you could do a GROUP BY email do only get one email.

If its a once off I would probably just turn off the auto_increment in your new mysql table id column until you have finished your migrations and then turn it back on or/ create another column called udid in the new database table (and then rename and delete the id col). Probably nicer ways to do it, but its fast and easy.