DROP TABLE IF EXISTS t1;

CREATE TABLE t1 (a DATETIME, b TIMESTAMP AS (TIMESTAMP(a)));

SHOW CREATE TABLE t1;

+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                                                                       |

+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| t1    | CREATE TABLE `t1` (

  `a` datetime DEFAULT NULL,

  `b` timestamp AS (timestamp(a)) VIRTUAL NULL ON UPDATE CURRENT_TIMESTAMP

) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+

MariaDB [test]> CREATE TABLE `t1` (`a` datetime DEFAULT NULL, `b` timestamp AS (timestamp(a)) VIRTUAL NULL ON UPDATE CURRENT_TIMESTAMP ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'NULL ON UPDATE CURRENT_TIMESTAMP ) ENGINE=InnoDB DEFAULT CHARSET=latin1' at line 1

MariaDB [test]>