change_column_sql

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 757
      def change_column_sql(table_name, column_name, type, options = {})
        column = column_for(table_name, column_name)

        unless options_include_default?(options)
          options[:default] = column.default
        end

        unless options.has_key?(:null)
          options[:null] = column.null
        end

        options[:name] = column.name
        schema_creation.accept ChangeColumnDefinition.new column, type, options
      end