Rails 3 - Using LIKE to search a combined 2 columns

I'm following ryan's Simple Search Form tutorial here: http://railscasts.com/episodes/37-simple-search-form

I have the following line in my Users Model:

find(:all, :conditions => ['fname LIKE ?', "%#{search}%"])

But what I'd like to do is search across 开发者_运维技巧a combine 2 columns,: fname & lname

As users are searching my full names:

Example, James Brown fname = James lname = Brown

Is there a way to do this in Rails safely that will work across DBs like SQLite, MySQL or Postgres (heroku uses)?

Thanks!

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It may not be pretty, but I use this in my Person model:

scope :by_full_name lambda {|q| 
    where("first_name LIKE ? or last_name LIKE ? or concat(last_name, ', ', first_name) LIKE ?", "%#{q}%", "%#{q}%" , "%#{q}%")
}

See one of my other posts for an bit extra that will let the search query be optional.

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This ended up working extremely well... Not sure about performance though. Can Indexes Help This?

:conditions => ['fname || lname LIKE ?', "%#{search}%"]