how to update a record without worrying about primary key

Question

In ActiveRecord how can we update a record without worrying/knowing primary key. If I do ``` Address.update(15, :user_name => 'Samuel') ``` it corresponds to ``` UPDATE addresses set user_name = 'Samuel' where id = 15 ``` but what if i want to do: ``` UPDATE addresses set user_name = 'Samuel' where cid = 15 ``` what will be the ActiveRecord equivalent of that?? I tried: ``` Address.update({:cid => 15}, :user_name => 'Samuel') ``` but that does not work.

Accepted Answer

```
a = Address.find_by_cid(15)
a.user_name = 'Samuel'
a.save
```

how to update a record without worrying about primary key

Solution

Problem