Hi. I edited the Virtual Columns page https://mariadb.com/kb/en/virtual-columns/ It said that ALTER TABLE was fully supported. I modified this way: ##ALTER TABLE##'s ##MODIFY## and ##CHANGE## clauses are supported for ##PERSISTENT## columns, but not for ##VIRTUAL## columns. This is based on the following test: MariaDB [(none)]> SELECT VERSION(); +--------------------+ | VERSION() | +--------------------+ | 10.0.4-MariaDB-log | +--------------------+ 1 row in set (0.07 sec) MariaDB [(none)]> DROP TABLE IF EXISTS `test`.`t`; Query OK, 0 rows affected (0.08 sec) MariaDB [(none)]> CREATE TABLE `test`.`t`(`c` INT, `v` INT) ENGINE = InnoDB; Query OK, 0 rows affected (0.17 sec) MariaDB [(none)]> ALTER TABLE `test`.`t` MODIFY COLUMN `v` INTEGER GENERATED ALW AYS AS (`c`+1) VIRTUAL; ERROR 1907 (HY000): This is not yet supported for computed columns MariaDB [(none)]> ALTER TABLE `test`.`t` MODIFY COLUMN `v` INTEGER GENERATED ALW AYS AS (`c`+1) PERSISTENT; Query OK, 0 rows affected (0.02 sec) Records: 0 Duplicates: 0 Warnings: 0 MariaDB [(none)]> ALTER TABLE `test`.`t` MODIFY COLUMN `v` INTEGER; Query OK, 0 rows affected (2.27 sec) Records: 0 Duplicates: 0 Warnings: 0 Federico