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[mysql] 컬럼 추가/삭제

Jaeyeon Baek 2013.03.21 16:30

◆ 컬럼 추가

   mysql> alter table 테이블_이름 add 컬럼_이름 타입 ;

mysql> desc new_table;

+-------+--------------+------+-----+---------+-------+

| Field   | Type             | Null   | Key | Default   | Extra  |

+-------+--------------+------+-----+---------+-------+

| title     | varchar(50)    | YES  |       | NULL     |          | 

| descr  | varchar(128)  | YES  |       | NULL     |          | 

+-------+--------------+------+-----+---------+-------+

2 rows in set (0.00 sec)


mysql> 

mysql> 

mysql> alter table new_table add num int(4) not null default 0;

Query OK, 0 rows affected (0.01 sec)

Records: 0  Duplicates: 0  Warnings: 0


mysql> desc new_table;

+-------+--------------+------+-----+---------+-------+

| Field   | Type             | Null   | Key | Default   | Extra   |

+-------+--------------+------+-----+---------+-------+

| title    | varchar(50)     | YES  |       | NULL     |           | 

| descr | varchar(128)   | YES  |       | NULL     |           | 

| num  | int(4)         | NO  |     | 0        |         | 

+-------+--------------+------+-----+---------+-------+

3 rows in set (0.00 sec)


mysql> 


◆ 컬럼 삭제

mysql> desc new_table;

+-------+--------------+------+-----+---------+-------+

| Field   | Type             | Null   | Key | Default    | Extra  |

+-------+--------------+------+-----+---------+-------+

| title    | varchar(50)     | YES  |       | NULL     |           | 

| descr | varchar(128)   | YES  |       | NULL     |           | 

| num   | int(4)             | NO    |       | 0           |           | 

+-------+--------------+------+-----+---------+-------+

3 rows in set (0.00 sec)


mysql> 

mysql> alter table new_table drop num;

Query OK, 0 rows affected (0.01 sec)

Records: 0  Duplicates: 0  Warnings: 0


mysql> desc new_table;

+-------+--------------+------+-----+---------+-------+

| Field   | Type             | Null   | Key  | Default   | Extra |

+-------+--------------+------+-----+---------+-------+

| title    | varchar(50)    | YES  |        | NULL      |         | 

| descr | varchar(128)   | YES |        | NULL      |         | 

+-------+--------------+------+-----+---------+-------+

2 rows in set (0.00 sec)


mysql>


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