Query OK, 0 rows affected (0.04 sec)
mysql> show tables;
+-------------------+
| Tables_in_test_db |
+-------------------+
| person_test |
+-------------------+
1 row in set (0.00 sec)
（15）新增主键
Mysql代码
mysql> alter table person_test add primary key(id);
Query OK, 0 rows affected (0.11 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc person_test;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id | int(11) | NO | PRI | 0 | |
| name | varchar(20) | YES | | NULL | |
| sex | char(8) | YES | | NULL | |
| birth | date | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
删除主键：
Mysql代码
mysql> alter table person_test drop primary key;
Query OK, 0 rows affected (0.18 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc person_test;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id | int(11) | NO | | 0 | |
| name | varchar(20) | YES | | NULL | |
| sex | char(8) | YES | | NULL | |
| birth | date | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
5 rows in set (0.01 sec)
（16）删除表
Mysql代码
mysql> drop table person_test;
Query OK, 0 rows affected (0.04 sec)
mysql> show tables;
Empty set (0.00 sec)
（17）删除数据库
Mysql代码
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test_db |
+--------------------+
5 rows in set (0.00 sec)
mysql> drop database test_db;
Query OK, 0 rows affected (0.11 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
（18）查看建表语句
mysql> show create table table_name;
补充说明：
update mysql.user set password="root" where User="root";修改的不是密码，如果按照这个方式修改了，重新登录时将会报错：
Mysql代码
mysql> update mysql.user set password="root" where User="root";
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> exit
Bye
C:\Users\liqiong>mysql -uroot -p
Enter password: ****
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: Y
ES)
请按照以下方式重新修改密码，即可登录成功：
Mysql代码
C:\Users\liqiong>mysql -uroot
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.5.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> update mysql.user set password=password("root") where User="root";
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye
C:\Users\liqiong>mysql -uroot -p
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.5.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2011, Oracle and