new_column_from_field

# File activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb, line 178
          def new_column_from_field(table_name, field, _definitions)
            field_name = field.fetch(:Field)
            type_metadata = fetch_type_metadata(field[:Type], field[:Extra])
            default, default_function = field[:Default], nil

            if type_metadata.type == :datetime && /\ACURRENT_TIMESTAMP(?:\([0-6]?\))?\z/.match?(default)
              default = "#{default} ON UPDATE #{default}" if /on update CURRENT_TIMESTAMP/.match?(field[:Extra])
              default, default_function = nil, default
            elsif type_metadata.extra == "DEFAULT_GENERATED"
              default = +"(#{default})" unless default.start_with?("(")
              default, default_function = nil, default
            elsif type_metadata.type == :text && default&.start_with?("'")
              # strip and unescape quotes
              default = default[1...-1].gsub("\\'", "'")
            elsif default&.match?(/\A\d/)
              # Its a number so we can skip the query to check if it is a function
            elsif default && default_type(table_name, field_name) == :function
              default, default_function = nil, default
            end

            MySQL::Column.new(
              field[:Field],
              default,
              type_metadata,
              field[:Null] == "YES",
              default_function,
              collation: field[:Collation],
              comment: field[:Comment].presence
            )
          end