mysql 操作表结构

show databases;    --显示所有的数据库

create database demo;    --创建了一个demo名的数据库

drop database demo;    --删除这个数据库

use demo;    --定位demo数据库，进入到里面

show tables;    --显示所有的表

--下面是创建一个表
DROP TABLE IF EXISTS `my_column`;
CREATE TABLE `my_column` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT ‘商品栏目id主建‘,
  `pid` int(10) NOT NULL DEFAULT ‘0‘ COMMENT ‘父级栏目‘,
  `uid` smallint(5) NOT NULL COMMENT ‘用户id‘,
  `title` char(50) NOT NULL COMMENT ‘栏目名‘,
  `img` varchar(255) DEFAULT NULL,
  `keyword` char(255) DEFAULT NULL COMMENT ‘栏目关键词‘,
  `description` char(255) DEFAULT NULL COMMENT ‘栏目描述‘,
  `create_time` int(11) unsigned NOT NULL,
  `sort` char(5) NOT NULL DEFAULT ‘50‘ COMMENT ‘排序‘,
  `status` smallint(3) NOT NULL DEFAULT ‘1‘ COMMENT ‘状态‘,
  PRIMARY KEY (`id`,`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=30 DEFAULT CHARSET=utf8;

---修改表结构

mysql> desc z_test;
+-------+------------------+------+-----+---------+----------------+
| Field | Type             | Null | Key | Default | Extra          |
+-------+------------------+------+-----+---------+----------------+
| id    | int(11) unsigned | NO   | PRI | NULL    | auto_increment |
| name  | varchar(255)     | NO   | UNI | NULL    |                |
| age   | int(11)          | NO   |     | NULL    |                |
| info  | varchar(255)     | NO   |     | NULL    |                |
+-------+------------------+------+-----+---------+----------------+
4 rows in set

mysql> alter table z_test add content text(255) after age;
Query OK, 0 rows affected
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc z_test;
+---------+------------------+------+-----+---------+----------------+
| Field   | Type             | Null | Key | Default | Extra          |
+---------+------------------+------+-----+---------+----------------+
| id      | int(11) unsigned | NO   | PRI | NULL    | auto_increment |
| name    | varchar(255)     | NO   | UNI | NULL    |                |
| age     | int(11)          | NO   |     | NULL    |                |
| content | text             | YES  |     | NULL    |                |
| info    | varchar(255)     | NO   |     | NULL    |                |
+---------+------------------+------+-----+---------+----------------+

--修改字段属性
alter table z_test modify content varchar(50);

--修改表中莫个列的名称，把age改为phone
alter table z_test change age phone int(11) not null;

--删除列
alter table z_test drop content;