drop table if exists t1;
CREATE TABLE t1 (a VARCHAR(5) COLLATE utf8_unicode_ci PRIMARY KEY)
ENGINE=InnoDB;
INSERT INTO t1 VALUES (0xEFBCA4EFBCA4EFBCA4);
DELETE FROM t1;
INSERT INTO t1 VALUES ('DDD');
SELECT * FROM t1;
a
DDD
DROP TABLE t1;