MariaDB [test]> create table t1 (columnname int);

Query OK, 0 rows affected (0.017 sec)

MariaDB [test]> alter table t1 rename column columnname to COLUMNNAME;

Query OK, 0 rows affected (0.001 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table t1\G

*************************** 1. row ***************************

       Table: t1

Create Table: CREATE TABLE `t1` (

  `columnname` int(11) DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1

1 row in set (0.001 sec)

MySQL [test]> create table t1 (columnname int);

Query OK, 0 rows affected (0.057 sec)

MySQL [test]> alter table t1 rename column columnname to COLUMNNAME;

Query OK, 0 rows affected (0.026 sec)

Records: 0  Duplicates: 0  Warnings: 0

MySQL [test]> show create table t1\G

*************************** 1. row ***************************

       Table: t1

Create Table: CREATE TABLE `t1` (

  `COLUMNNAME` int DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

1 row in set (0.001 sec)