SQL ALTER

id	title	price	amount
1	short_pants	30000	5
2	blue_jeans	50000	20
3	skirt	60000	10
4	short_t_shirt	15000	10

Table Field 추가

ALTER TABLE mysql_test_a ADD note TEXT;

Field	Type	Null	Key	Default	Extra
id	int	NO	PRI		auto_increament
title	varchar(30)	NO
price	int	NO
amount	int	NO
note	text	YES

Table Field 변경

ALTER TABLE mysql_test_a MODIFY note VARCHAR(100);

Field	Type	Null	Key	Default	Extra
id	int	NO	PRI		auto_increament
title	varchar(30)	NO
price	int	NO
amount	int	NO
note	varchar(100)	YES

Table Field 명 변경

ALTER TABLE mysql_test_a CHANGE COLUMN note refer VARCHAR(100);

Field	Type	Null	Key	Default	Extra
id	int	NO	PRI		auto_increament
title	varchar(30)	NO
price	int	NO
amount	int	NO
refer	varchar(100)	YES

Table Field 삭제

ALTER TABLE mysql_test_a DROP COLUMN refer;

Field	Type	Null	Key	Default	Extra
id	int	NO	PRI		auto_increament
title	varchar(30)	NO
price	int	NO
amount	int	NO