change_column

# File activerecord/lib/active_record/connection_adapters/mysql_adapter.rb, line 449
      def change_column(table_name, column_name, type, options = {}) #:nodoc:
        unless options_include_default?(options)
          if column = columns(table_name).find { |c| c.name == column_name.to_s }
            options[:default] = column.default
          else
            raise "No such column: #{table_name}.#{column_name}"
          end
        end

        change_column_sql = "ALTER TABLE #{quote_table_name(table_name)} CHANGE #{quote_column_name(column_name)} #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
        add_column_options!(change_column_sql, options)
        execute(change_column_sql)
      end