MYSQL: Want to make a date column NULL

I have some changes to a Django app using a mysql database backend. I have been receiving this error.

(1048, "Column 'current_item_status_date' cannot be null")

I have tried to 开发者_Python百科make it NULL by using the ALTER TABLE command, but this is not working. Saying there is an invalid syntax.

ALTER TABLE tiptop_items MODIFY current_item_status_date null;

ALTER TABLE tiptop_items MODIFY current_item_status_date DATE NULL;