语法为:
ALTER TABLE table_name ADD COLUMN new_column_name data_type NULL|NOT NULL DEFAULT def_value
ALTER TABLE actor ADD COLUMN create_date datetime NOT NULL DEFAULT '2020-10-01 00:00:00'
语法为:
ALTER TABLE table_name ADD COLUMN new_column_name data_type NULL|NOT NULL DEFAULT def_value
ALTER TABLE actor ADD COLUMN create_date datetime NOT NULL DEFAULT '2020-10-01 00:00:00'