程序媛计划——mysql修改表结构

Posted 2020-10-06 IcarusYu

#查看表的结构

mysql> desc score;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(4)       | NO   | PRI | NULL    | auto_increment |
| name       | char(20)     | NO   |     | NULL    |                |
| score      | double(16,2) | YES  |     | NULL    |                |
| evaluation | char(20)     | YES  |     | normal  |                |
+------------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

 

 

#alter对字段操作

#添加字段

mysql> alter table exam_score add other int(4) default 10;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

#修改字段变为另一个字段

mysql> alter table exam_score change other evaluation char(20) default ‘normal‘; 
Query OK, 4 rows affected (0.02 sec)
Records: 4  Duplicates: 0  Warnings: 0

#删除字段(即删除字段中的所有数据)

mysql> alter table exam_score drop column other;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

 

#修改表名

mysql> rename table exam_score to score;
Query OK, 0 rows affected (0.01 sec)