mysql随笔系列-1

Posted 2020-11-07 我是大空翼

mysql数据库管理

　　本人实验所用的MySQL数据库版本：5.5.56-MariaDB MariaDB Server  操作系统：centos7.5

　　1.创建数据库

　　　　MariaDB [(none)]> create database test1;

　　2.查看所有数据库

　　　　MariaDB [(none)]> show databases;

　　　　

+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test1 |
+--------------------+
5 rows in set (0.00 sec)

 

 

    3.创建指定字符集数据库

　　　　查看库的字符集和校对规则：

　　　　　　MariaDB [(none)]> show character set;

　　　　　　

+----------+-----------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+-----------------------------+---------------------+--------+
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |

...................................................................略

 

　　　　实例：创建一个库，指定字符集为utf8

　　　　　　　　

MariaDB [(none)]> create database test2_utf8 character set utf8 collate utf8_general_ci;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> show create database test2_utf8;
+------------+---------------------------------------------------------------------+
| Database | Create Database |
+------------+---------------------------------------------------------------------+
| test2_utf8 | CREATE DATABASE `test2_utf8` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+------------+---------------------------------------------------------------------+
1 row in set (0.00 sec)

 

    4.删除数据库

　　　　

MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test1 |
| test2_utf8 |
+--------------------+
6 rows in set (0.00 sec)

MariaDB [(none)]> drop database test1;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test2_utf8 |
+--------------------+
5 rows in set (0.01 sec)

上述所示：删除数据库test1成功！

     5.进入数据库中指定的库

　　　　

MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test2_utf8 |
+--------------------+
5 rows in set (0.00 sec)

MariaDB [(none)]> use test2_utf8;
Database changed
MariaDB [test2_utf8]> select database();
+------------+
| database() |
+------------+
| test2_utf8 |
+------------+
1 row in set (0.00 sec)

     6.查看进入当前数据库的用户

　　　　

MariaDB [test2_utf8]> select user();
+----------------+
| user() |
+----------------+
| [email protected] |
+----------------+
1 row in set (0.00 sec)

    7.删除数据库中的账号

　　　　语法：drop user ‘user’@’主机域0 ’  <--注意引号，可以是单或双引号，但是不能不加。

　　　　

MariaDB [mysql]> select database();
+------------+
| database() |
+------------+
| mysql |
+------------+
1 row in set (0.00 sec)

MariaDB [mysql]> select user,host from mysql.user;
+------+-----------------------+
| user | host |
+------+-----------------------+
| root | 127.0.0.1 |
| root | ::1 |
| | localhost |
| root | localhost |
| | localhost.localdomain |
| root | localhost.localdomain |
+------+-----------------------+
6 rows in set (0.00 sec)

MariaDB [mysql]> drop user ‘root‘@‘::1‘;
Query OK, 0 rows affected (0.00 sec)

MariaDB [mysql]> select user,host from mysql.user;
+------+-----------------------+
| user | host |
+------+-----------------------+
| root | 127.0.0.1 |
| | localhost |
| root | localhost |
| | localhost.localdomain |
| root | localhost.localdomain |
+------+-----------------------+
5 rows in set (0.00 sec)

     8.查看数据库的用户

　　　　

MariaDB [mysql]> select user,host from mysql.user;
+------+-----------------------+
| user | host |
+------+-----------------------+
| root | 127.0.0.1 |
| | localhost |
| root | localhost |
| | localhost.localdomain |
| root | localhost.localdomain |
+------+-----------------------+
5 rows in set (0.00 sec)