ruby on rails - Syntax for changing activerecord data type on command line -

I have an active recorder table called processors with strings along with all the columns. I want to convert a column to float. What is the syntax for doing this on the command line? Is there something like this:

  RailG migration change_avg_submitted_charges_in_procedures_float    
 
 < P> Yes, this will generate the migration file. Then edit the file to read some:  
  change_column: table_name,: column_name,: float   
 then run  
  Rack DB: Migrate