ALTER TABLE `subject_course` ADD COLUMN `reference` VARCHAR(45) NULL DEFAULT NULL AFTER `options_sbc`;
ALTER TABLE `activity` CHANGE COLUMN `act_reference` `act_reference` VARCHAR(45) NULL DEFAULT NULL ;
ALTER TABLE `user` ADD COLUMN `google_token` TEXT NULL DEFAULT NULL AFTER `updated_data`;
ALTER TABLE `optional_subject` ADD COLUMN `reference` VARCHAR(45) NULL DEFAULT NULL AFTER `abilities_osb`;
ALTER TABLE `opt_activity` CHANGE COLUMN `opa_reference` `opa_reference` VARCHAR(45) NULL DEFAULT NULL ;

CREATE TABLE `google_credential` (
  `serial_goc` INT(11) NOT NULL AUTO_INCREMENT,
  `type` ENUM('OAUTH2', 'SERVICE_ACCOUNT', 'NONE') NOT NULL DEFAULT 'NONE',
  `credentials_json` TEXT NOT NULL,
  PRIMARY KEY (`serial_goc`));


ALTER TABLE `google_credential`
ADD COLUMN `create_class` ENUM('YES','NO') NOT NULL DEFAULT 'YES' AFTER `credentials_json`;