sql> alter table bad_item_node modify parent_id bigint(19) null;
(Update count: 0, 3 ms)
sql> show columns from bad_item_node;
FIELD     | TYPE       | NULL | KEY | DEFAULT
ITEM_ID   | BIGINT(19) | NO   | PRI | NULL
TREE_ID   | BIGINT(19) | NO   | PRI | NULL
PARENT_ID | BIGINT(19) | YES  |     | NULL

sql> alter table bad_thing modify current_thing_data timestamp(23) null;
(Update count: 0, 56 ms)
sql> show columns from bad_thing;
FIELD              | TYPE          | NULL | KEY | DEFAULT
ID                 | BIGINT(19)    | NO   | PRI | (NEXT VALUE FOR PUBLIC.SYSTEM_SEQUENCE_142D3DF4_1A8A_4A2E_AA4D_7FDCD5BB32C4)
LOCK               | INTEGER(10)   | NO   |     | NULL
NAME               | VARCHAR(255)  | NO   | UNI | NULL
CURRENT_THING_DATA | TIMESTAMP(23) | YES  |     | NULL