ALTER TABLE `mapping_rules`
	ALTER `table_name` DROP DEFAULT,
	ALTER `key_name` DROP DEFAULT,
	ALTER `key_value` DROP DEFAULT,
	ALTER `ext_table_name` DROP DEFAULT,
	ALTER `ext_key_name` DROP DEFAULT,
	ALTER `ext_key_value` DROP DEFAULT;

ALTER TABLE `mapping_rules`
	CHANGE COLUMN `table_name` `table_name` VARCHAR(255) NOT NULL,
	CHANGE COLUMN `key_name` `key_name` VARCHAR(255) NOT NULL,
	CHANGE COLUMN `key_value` `key_value` VARCHAR(255) NOT NULL,
	CHANGE COLUMN `ext_table_name` `ext_table_name` VARCHAR(255) NOT NULL,
	CHANGE COLUMN `ext_key_name` `ext_key_name` VARCHAR(255) NOT NULL,
	CHANGE COLUMN `ext_key_value` `ext_key_value` VARCHAR(255) NOT NULL;
