MySQL에서 외래 키 제약 조건이 있는 테이블을 자르는 방법은 무엇입니까?

ERROR 1701 (42000): Cannot truncate a table referenced in a foreign key constraint (mytest.instance, CONSTRAINT instance_ibfk_1 FOREIGN KEY (GroupID) REFERENCES mytest.mygroup (ID))

CREATE TABLE mygroup (
   ID    INT NOT NULL AUTO_INCREMENT PRIMARY KEY
) ENGINE=InnoDB;

CREATE TABLE instance (
   ID           INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
   GroupID      INT NOT NULL,
   DateTime     DATETIME DEFAULT NULL,

   FOREIGN KEY  (GroupID) REFERENCES mygroup(ID) ON DELETE CASCADE,
   UNIQUE(GroupID)
) ENGINE=InnoDB;

SET FOREIGN_KEY_CHECKS = 0;

TRUNCATE mygroup;
TRUNCATE instance;

SET FOREIGN_KEY_CHECKS = 1;

DELETE FROM mygroup;
DELETE FROM instance;