MySQL 8.0

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CREATE TABLE `test` (
  `id` mediumint NOT NULL AUTO_INCREMENT,
  `Date_VARCHAR` varchar(30) DEFAULT NULL,
--  `Date_TIMESTAMP` timestamp(6) NULL DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=52383 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
CREATE TRIGGER tr 
BEFORE INSERT
ON test
FOR EACH ROW
SET NEW.Date_VARCHAR = STR_TO_DATE(NEW.Date_VARCHAR, '%Y-%m-%dT%h-%i-%s');
INSERT INTO test (`Date_VARCHAR`)
VALUES('2021-05-10T08-45-30'), ('2021-05-10T08-46-30'), ('2021-05-10T08-47-30'), ('2021-05-10T08-48-30');
SELECT * FROM test;


id
Date_VARCHAR


52383
2021-05-10 08:45:30

52384
2021-05-10 08:46:30

52385
2021-05-10 08:47:30

52386
2021-05-10 08:48:30

id	Date_VARCHAR
52383	2021-05-10 08:45:30
52384	2021-05-10 08:46:30
52385	2021-05-10 08:47:30
52386	2021-05-10 08:48:30