dump of on update missing fraction

[elvizlai]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.
   create table xyz using:

CREATE TABLE `xyz` (
  `id` varchar(36) NOT NULL,
  `create_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  `update_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (`id`)
);

then using mysql dump to extract structure.

2. What did you expect to see（result from circleci/mysql:5.7）?

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for xyz
-- ----------------------------
DROP TABLE IF EXISTS `xyz`;
CREATE TABLE `xyz` (
  `id` varchar(36) COLLATE utf8_unicode_ci NOT NULL,
  `create_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  `update_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP(3),
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

SET FOREIGN_KEY_CHECKS = 1;

3. What did you see instead(result from TiDB)?

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for xyz
-- ----------------------------
DROP TABLE IF EXISTS `xyz`;
CREATE TABLE `xyz` (
  `id` varchar(36) NOT NULL,
  `create_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
  `update_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

SET FOREIGN_KEY_CHECKS = 1;

The ON UPDATE CURRENT_TIMESTAMP missing fraction

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   3.0.1

5. Addon

explicit-defaults-for-timestamp has set ON

[winkyao]

@elvizlai Thanks for your report, @bb7133 will try to fix this issue.

[bb7133]

This issue is related to #11070, however, the ON_UPDATE CURRENT_TIMESTAMP parted is not fixed.