非空約束2(CHAR(2)數據太小會出錯)
ALTER TABLE books MODIFY title VARCHAR(50) NOT NULL;blog
---取消非空
ALTER TABLE books MODIFY title VARCHAR(50) NULL;it
ALTER TABLE books MODIFY sex CHAR(2) NOT NULL;im
Data truncated for column 'sex' at row 1數據
CHAR(2)數據太小會出錯img