Is there a way to refactor this code? I'm new to ruby on rails, on this project I'm using Ruby 2.0 and Ruby on Rails 3.0.

I would like to know if this piece of code can be refactored, as it is

unless params["ot_code"].nil?       
  ots = params["ot_code"].gsub(/\r\n?/, "").gsub(";","','").upcase
  ots[ots.length,1] = "'"
  ots =  ots.rjust(ots.length+1,"'")
end

unless params["circuit_id_multiple"].nil?
   multiple_circuit = params["circuit_id_multiple"].gsub(/\r\n?/, "").gsub(";","','")
   multiple_circuit[multiple_circuit.length,1] = "'"
   multiple_circuit = multiple_circuit.rjust(multiple_circuit.length+1,"'")
end

unless params["multiple_element_code"].nil?
   multiple_element_code = params["multiple_element_code"].gsub(/\r\n?/, "").gsub(";","','")
   multiple_element_code[multiple_element_code.length,1] = "'"
   multiple_element_code = multiple_element_code.rjust(multiple_element_code.length+1,"'")
end
I'm a little worried about your gsubs, but assuming this is what you want to do:

def replace_and_wrap(str)
  return nil if str.nil?
  %Q{'#{str.gsub(/\r\n?/, "").gsub(";","','")}'}  
end

ots = replace_and_wrap(params["ot_code"])
multiple_circuit = replace_and_wrap(params["circuit_id_multiple"])
multiple_element_code = replace_and_wrap(params["multiple_element_code"])


Note that this changes the behavior of your code slightly: variables (like ots) are set to nil if the param is nil, rather than remaining undefined. Depending on how you are using these variables, this behavior is probably better anyway.