数据表中增加、删除字段表名修改

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接上篇文章《修改、删除数据库表数据》，修改数据库中表名，表中增加、删除字段。

mysql> use gbk    #进入gbk数据库
mysql> desc test;
+-------+----------+------+-----+---------+----------------+
| Field | Type     | Null | Key | Default | Extra          |
+-------+----------+------+-----+---------+----------------+
| id    | int(4)   | NO   | PRI | NULL    | auto_increment |
| name  | char(20) | NO   |     | NULL    |                |
+-------+----------+------+-----+---------+----------------+
mysql> alter table test add gender char(4);    #增加gender
mysql> desc test;
+--------+----------+------+-----+---------+----------------+
| Field  | Type     | Null | Key | Default | Extra          |
+--------+----------+------+-----+---------+----------------+
| id     | int(4)   | NO   | PRI | NULL    | auto_increment |
| name   | char(20) | NO   |     | NULL    |                |
| gender | char(4)  | YES  |     | NULL    |                |
+--------+----------+------+-----+---------+----------------+
mysql> alter table test add age int(4) after name;
mysql> desc test;
+--------+----------+------+-----+---------+----------------+
| Field  | Type     | Null | Key | Default | Extra          |
+--------+----------+------+-----+---------+----------------+
| id     | int(4)   | NO   | PRI | NULL    | auto_increment |
| name   | char(20) | NO   |     | NULL    |                |
| age    | int(4)   | YES  |     | NULL    |                |
| gender | char(4)  | YES  |     | NULL    |                |
+--------+----------+------+-----+---------+----------------+
mysql> show tables;
+---------------+
| Tables_in_gbk |
+---------------+
| test          |
+---------------+
mysql> rename table test to hello;
mysql> show tables;
+---------------+
| Tables_in_gbk |
+---------------+
| hello         |
+---------------+
mysql> alter table hello rename to world;
mysql> show tables;
+---------------+
| Tables_in_gbk |
+---------------+
| world         |
+---------------+
mysql> alter table world drop age;
mysql> desc world;
+--------+----------+------+-----+---------+----------------+
| Field  | Type     | Null | Key | Default | Extra          |
+--------+----------+------+-----+---------+----------------+
| id     | int(4)   | NO   | PRI | NULL    | auto_increment |
| name   | char(20) | NO   |     | NULL    |                |
| gender | char(4)  | YES  |     | NULL    |                |
+--------+----------+------+-----+---------+----------------+
3 rows in set (0.00 sec)