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NSD DBA1 DAY01

  1. 构建MySQL服务器
  2. 数据库基本管理
  3. MySQL 数据类型

1 构建MySQL服务器

1.1 问题

本案例要求熟悉MySQL官方安装包的使用,快速构建一台数据库服务器:

1.2 方案

本课程将使用64位的RHEL 7操作系统,MySQL数据库的版本是5.7.17。

访问http://dev.mysql.com/downloads/mysql/,找到MySQL Community Server下载页面,平台选择“Red Hat Enterprise Linux 7/ Oracle Linux”,然后选择64位的bundle整合包下载,如图-1所示。

图-1

注意:下载MySQL软件时需要以Oracle网站账户登录,如果没有请根据页面提示先注册一个(免费)

1.3 步骤

实现此案例需要按照如下步骤进行。

步骤一:准备工作

1)停止mariadb服务

[root@localhost ~]# systemctl  stop mariadb

2)删除/etc/my.cnf配置文件

此配置文件由RHEL自带的mariadb-libs库提供:

[root@localhost ~]# rm -rf /etc/my.cnf

3)删除数据

 [root@localhost ~]# rm -rf /var/lib/mysql/*

4)卸载软件包(没有会显示未安装软件包)

 [root@localhost ~]# rpm -e --nodeps mariadb-server mariadb 
警告:/var/log/mariadb/mariadb.log 已另存为/var/log/mariadb/mariadb.log.rpmsave

步骤二:安装软件包

1)安装mysql时可能会缺少某些依赖包,需提前单独安装

#cold_bold [root@localhost ~]# yum -y install perl-Data-Dumper  perl-JSON  perl-Time-HiRes

2)物理机传输解压包给虚拟机192.168.4.1

[root@room9pc01 ~]# cd 桌面            
[root@room9pc01 桌面]# scp mysql-5.7.17.tar 192.168.4.1:/root/  //给虚拟机传包
root@192.168.4.1's password:
mysql-5.7.17.tar     100%  543MB  95.6MB/s   00:05

3)虚拟机192.168.4.1解压mysql-5.7.17.tar 整合包

#cold_bold[root@localhost ~]# tar -xvf mysql-5.7.17.tar               //解压mysql整合包
#cold_bold./mysql-community-client-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-common-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-devel-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-embedded-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-embedded-compat-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-embedded-devel-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-libs-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-libs-compat-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-minimal-debuginfo-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-server-5.7.17-1.el7.x86_64.rpm
#cold_bold./mysql-community-test-5.7.17-1.el7.x86_64.rpm

步骤三:启动MySQL数据库服务并设置开机自启

[root@localhost ~]# systemctl start mysqld                  //启动mysql服务
[root@localhost ~]# systemctl enable mysqld                 //设置开机自启
[root@localhost ~]# systemctl status mysqld                 //查看mysql服务状态
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 二 2018-08-28 10:03:24 CST; 8min ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
 Main PID: 4284 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─4284 /usr/sbin/mysqld --daemonize --pid-file=/var/r...

8月 28 10:02:56 localhost.localdomain systemd[1]: Starting MySQ...
8月 28 10:03:24 localhost.localdomain systemd[1]: Started MySQL...
Hint: Some lines were ellipsized, use -l to show in full.

步骤四:连接MySQL服务器,修改密码

查看随机生成的root管理密码

[root@localhost ~]#grep 'temporary password' /var/log/mysqld.log
2017-04-01T18:10:42.948679Z 1 [Note] A temporary password is generated for root@localhost: mtoa>Av<p6Yk        //随机生成的管理密码为mtoa>Av<p6Yk

2)使用客户端命令mysql连接到MySQL服务器

提示验证时,填入前一步获得的随机密码,验证成功后即可进入“mysql> ”环境:

[root@localhost ~]# mysql -u root -p'mtoa>Av<p6Yk'
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.17

Copyright (c) 2000, 2016, 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> 									//登录成功后,进入SQL操作环境

用该密码登录到服务端后,必须马上修改密码,不然会报如下错误:

mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

3)执行SET PASSWORD命令修改密码

这个其实与validate_password_policy的值有关,默认为1,所以刚开始设置的密码必须符合长度,且必须含有数字,小写或大写字母,特殊字符。如果我们不希望密码设置的那么复杂,需要修改两个全局参数:validate_password_policy与validate_password_length。validate_password_length默认值为8,最小值为4,如果你显性指定validate_password_length的值小于4,尽管不会报错,但validate_password_length的值将设为4。

可参考下列指令:

mysql>set global validate_password_policy=0;      //只验证长度
Query OK, 0 rows affected (0.00 sec)
mysql>set global validate_password_length=6;     //修改密码长度,默认值是8个字符 
Query OK, 0 rows affected (0.00 sec)
mysql> alter user user() identified by "123456";  //修改登陆密码
Query OK, 0 rows affected (0.00 sec)

上述操作的结果是——更改数据库用户root从本机访问时的密码,设为123456。

退出“mysql> ”环境,重新登录验证,必须采用新的密码才能登入:

mysql> exit  								//退出 mysql> 环境
Bye
[root@localhost ~]# mysql -u root -p		//重新登录
Enter password:  							//输入新设置的密码
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.7.17 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, 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.

2 数据库基本管理

2.1 问题

本案例要求熟悉MySQL的连接及数据库表的增删改查等基本管理操作,主要完成以下几个方便的操作:

表-1 测试用表数据

2.2 步骤

实现此案例需要按照如下步骤进行。

步骤一:使用mysql命令连接数据库

连接MySQL服务器时,最基本的用法是通过 -u 选项指定用户名、-p指定密码。密码可以写在命令行(如果不写,则出现交互,要求用户输入),当然基于安全考虑一般不推荐这么做:

[root@dbsvr1 ~]# mysql -uroot -p123456  		//紧挨着选项,不要空格
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 5.7.17 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, 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> exit  								//退出已登录的mysql> 环境
Bye

默认情况下,msyql命令会连接本机的MySQL服务。但在需要的时候,可以通过 -h 选项指定远程主机;

[root@dbsvr1 ~]# mysql -h 127.0.0.1 –u root –p 
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 17
Server version: 5.7.17 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, 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> exit  								//退出已登录的mysql环境
Bye

步骤二:练习查看/删除/创建库的相关操作

以root用户登入“mysql> ”环境后,可以执行各种MySQL指令、SQL指令。基本的用法事项如下:

1)查看现有的库

mysql> show  databases;                                //查看现有的库
+--------------------+
| Database            |
+--------------------+
| information_schema |  							//信息概要库
| mysql               |  							//授权库
| performance_schema |  							//性能结构库
| sys                  |  							//系统元数据库
+--------------------+
4 rows in set (0.15 sec)

2)切换/使用指定的库

mysql> use sys;                                        //切换到sys库
Database changed
mysql> select database(); 						   //确认当前所在的库
+------------+
| DATABASE() |
+------------+
| sys         |
+------------+
1 row in set (0.00 sec)

切换到mysql库:

mysql> use mysql;                                      //切换到mysql库
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select database();  						//确认当前所在的库
+------------+
| DATABASE() |
+------------+
| mysql      |
+------------+
1 row in set (0.00 sec)
5 rows in set (0.00 sec)

3)新建名为newdb的库,确认结果:

mysql> create database newdb;                     //新建名为newdb的库
Query OK, 1 row affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database            |
+--------------------+
| information_schema |
| mydb                |  						//新建的mydb库
| mysql               |
| newdb               |  						//新建的newdb库
| performance_schema |
| sys                 |
+--------------------+
6 rows in set (0.00 sec)

4)删除指定的库

mysql> drop database newdb;                       //删除名为newdb的库
Query OK, 0 rows affected (0.01 sec)

mysql> show databases; 						//确认删除结果,已无newdb库
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mydb               |
| mysql              |
| performance_schema |
| sys                 |
+--------------------+
5 rows in set (0.00 sec)

步骤三:练习查看/删除/创建表的相关操作

1)查看指定的库里有哪些表

查看mysql库里有哪些表:

mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+---------------------------+
| Tables_in_mysql           |
+---------------------------+
| columns_priv              |
| db                        |
| engine_cost               |
| event                     |
| func                      |
| general_log               |
| gtid_executed             |
| help_category             |
| help_keyword              |
| help_relation             |
| help_topic                |
| innodb_index_stats        |
| innodb_table_stats        |
| ndb_binlog_index          |
| plugin                    |
| proc                      |
| procs_priv                |
| proxies_priv              |
| server_cost               |
| servers                   |
| slave_master_info         |
| slave_relay_log_info      |
| slave_worker_info         |
| slow_log                  |
| tables_priv               |
| time_zone                 |
| time_zone_leap_second     |
| time_zone_name            |
| time_zone_transition      |
| time_zone_transition_type |
| user                      |                     //存放数据库用户的表
+---------------------------+
31 rows in set (0.00 sec)

2)查看指定表的字段结构

当前库为mysql,查看columns_priv表的结构,以列表形式展现:

mysql> desc columns_priv\G  		//查看表结构,以列表形式展现,末尾不用分号
*************************** 1. row ***************************
  Field: Host
   Type: char(60)
   Null: NO
    Key: PRI
Default: 
  Extra: 
*************************** 2. row ***************************
  Field: Db
   Type: char(64)
   Null: NO
    Key: PRI
Default: 
  Extra: 
*************************** 3. row ***************************
  Field: User
   Type: char(32)
   Null: NO
    Key: PRI
Default: 
  Extra: 
*************************** 4. row ***************************
  Field: Table_name
   Type: char(64)
   Null: NO
    Key: PRI
Default: 
  Extra: 
*************************** 5. row ***************************
  Field: Column_name
   Type: char(64)
   Null: NO
    Key: PRI
Default: 
  Extra: 
*************************** 6. row ***************************
  Field: Timestamp
   Type: timestamp
   Null: NO
    Key: 
Default: CURRENT_TIMESTAMP
  Extra: on update CURRENT_TIMESTAMP
*************************** 7. row ***************************
  Field: Column_priv
   Type: set('Select','Insert','Update','References')
   Null: NO
    Key: 
Default: 
  Extra: 
7 rows in set (0.01 sec)

查看columns_priv表的结构,以表格形式展现:

mysql> desc columns_priv;  		//查看表结构,以表格形式展现末尾需要有分号
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
| Field       | Type                                         | Null | Key | Default           | Extra                       |
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
| Host        | char(60)                                     | NO   | PRI |                   |                             |
| Db          | char(64)                                     | NO   | PRI |                   |                             |
| User        | char(32)                                     | NO   | PRI |                   |                             |
| Table_name  | char(64)                                     | NO   | PRI |                   |                             |
| Column_name | char(64)                                     | NO   | PRI |                   |                             |
| Timestamp   | timestamp                                    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| Column_priv | set('Select','Insert','Update','References') | NO   |     |                   |                             |
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
7 rows in set (0.00 sec)

上述操作中,当引用非当前库中的表时,可以用“库名.表名”的形式。比如,切换为mysql库再执行“desc columns_priv;”,与以下操作的效果是相同的:

mysql> desc mysql.columns_priv;
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
| Field       | Type                                         | Null | Key | Default           | Extra                       |
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
| Host        | char(60)                                     | NO   | PRI |                   |                             |
| Db          | char(64)                                     | NO   | PRI |                   |                             |
| User        | char(16)                                     | NO   | PRI |                   |                             |
| Table_name  | char(64)                                     | NO   | PRI |                   |                             |
| Column_name | char(64)                                     | NO   | PRI |                   |                             |
| Timestamp   | timestamp                                    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| Column_priv | set('Select','Insert','Update','References') | NO   |     |                   |                             |
+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+
7 rows in set (0.00 sec)

3)在test库中创建一个名为pwlist的表

包括name、password两列,其中name列作为主键。两个字段值均不允许为空,其中密码列赋予默认空值,相关操作如下所述。

切换到mydb库:

mysql> use mydb;
Database changed

新建pwlist表:

mysql> create table pwlist(
    -> name char(16) not null,
    -> password char(48)default '',
    -> primary key(name)
    -> );
Query OK, 0 rows affected (0.38 sec)

确认新创建的表:

mysql> show tables; 
+----------------+
| Tables_in_mydb |
+----------------+
| pwlist         |  								//新建的pwlist表
+----------------+
1 rows in set (0.01 sec)

查看pwlist表的字段结构:

mysql> desc pwlist;
+----------+----------+------+-----+---------+-------+
| Field    | Type     | Null | Key | Default | Extra |
+----------+----------+------+-----+---------+-------+
| name     | char(16) | NO   | PRI | NULL    |       |
| password | char(48) | YES  |     |         |       |
+----------+----------+------+-----+---------+-------+
2 rows in set (0.01 sec)

4)删除指定的表

删除当前库中的pwlist表:

mysql> drop table pwlist;
Query OK, 0 rows affected (0.01 sec)

确认删除结果:

mysql> show tables;
Empty set (0.00 sec)

5)在mydb库中创建一个学员表

表格结构及数据内容如表-1所示。

在MySQL表内存储中文数据时,需要更改字符集(默认为latin1不支持中文),以便MySQL支持存储中文数据记录;比如,可以在创建库或表的时候,手动添加“DEFAULT CHARSET=utf8”来更改字符集。

根据上述表格结构,创建支持中文的student表:

mysql> CREATE TABLE mydb.student(
    -> 学号 char(9) NOT NULL,
    -> 姓名 varchar(4) NOT NULL,
    -> 性别 enum('男','女') NOT NULL,
    -> 手机号 char(11) DEFAULT '',
    -> 通信地址 varchar(64),
    -> PRIMARY KEY(学号)
    -> ) DEFAULT CHARSET=utf8;  				//手工指定字符集,采用utf8
Query OK, 0 rows affected (0.31sec)

查看student表的字段结构:

mysql> DESC mydb.student;
+--------------+-------------------+------+-----+---------+-------+
| Field        | Type              | Null | Key | Default | Extra |
+--------------+-------------------+------+-----+---------+-------+
| 学号         | char(9)           | NO   | PRI | NULL    |       |
| 姓名         | varchar(4)        | NO   |     | NULL    |       |
| 性别         | enum('男','女')   | NO   |     | NULL    |       |
| 手机号       | char(11)          | YES  |     |         |       |
| 通信地址     | varchar(64)       | YES  |     | NULL    |       |
+--------------+-------------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

查看student表的实际创建指令:

mysql> SHOW CREATE TABLE mydb.student;
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|Table |Create Table                                                                                                                                                                                                                                                             |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student | CREATE TABLE `student` (
  `学号` char(9) NOT NULL,
  `姓名` varchar(4) NOT NULL,
  `性别` enum('男','女') NOT NULL,
  `手机号` char(11) DEFAULT '',
  `通信地址` varchar(64) DEFAULT NULL,
  PRIMARY KEY (`学号`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8                  |
+---------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

注意:若要修改MySQL服务的默认字符集,可以更改服务器的my.cnf配置文件,添加character_set_server=utf8 配置,然后重启数据库服务。

[root@dbsvr1 ~]# vim /etc/my.cnf  						//修改运行服务配置
[mysqld]
.. ..
character_set_server=utf8

[root@dbsvr1 ~]# systemctl restart mysqld  				//重启服务
.. ..
[root@dbsvr1 ~]# mysql –u root -p  
Enter password:
.. ..
mysql> SHOW VARIABLES LIKE 'character%';  				//确认更改结果
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                          |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.03 sec)

3 MySQL 数据类型

3.1 问题

3.2 步骤

实现此案例需要按照如下步骤进行。

步骤一:创建studb库、stuinfo表

1)新建studb库,并切换到studb库

mysql> CREATE DATABASE studb;
Query OK, 1 row affected (0.00 sec)
mysql> USE studb;
Database changed

2)新建stuinfo表

假定stuinfo表用来记录每个家庭成员的姓名(name)、性别(gender)、出生日期(birth)、职业(job)、与户主关系(relation)。

mysql> CREATE TABLE stuinfo (
    -> name varchar(16) NOT NULL,
    -> gender enum('male','femal') DEFAULT 'male',
    -> birth date NOT NULL,
    -> job varchar(16) DEFAULT '',
    -> relation varchar(24) NOT NULL,
    -> PRIMARY KEY(name)
    -> );
Query OK, 0 rows affected (0.61sec)

查看stuinfo表的字段结构:

mysql> DESC stuinfo;
+----------+----------------------+------+-----+---------+-------+
| Field    | Type                 | Null | Key | Default | Extra |
+----------+----------------------+------+-----+---------+-------+
| name     | varchar(16)          | NO   | PRI | NULL    |       |
| gender   | enum('male','femal') | YES  |     | male    |       |
| birth    | date                 | NO   |     | NULL    |       |
| job      | varchar(16)          | YES  |     |         |       |
| relation | varchar(24)          | NO   |     | NULL    |       |
+----------+----------------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

步骤二:练习各种时间函数的使用

1)使用now()查看当前的日期和时间

mysql> SELECT now();
+---------------------+
| now()               |
+---------------------+
| 2017-04-02 04:02:42 |
+---------------------+
1 row in set (0.00 sec)

2)使用sysdate()查看系统日期和时间

mysql> SELECT sysdate();
+---------------------+
| sysdate()           |
+---------------------+
| 2017-04-02 04:03:21 |
+---------------------+
1 row in set (0.00 sec)

3)使用curdate()获得当前的日期,不含时间

mysql> SELECT curdate();
+------------+
| curdate()  |
+------------+
| 2017-04-02 |
+------------+
1 row in set (0.00 sec)

4)使用curtime()获得当前的时间,不含日期

mysql> SELECT curtime();
+-----------+
| curtime() |
+-----------+
| 04:04:55  |
+-----------+
1 row in set (0.00 sec)

5)分别获取当前日期时间中的年份、月份、日

mysql> SELECT year(now()),month(now()),day(now());
+-------------+--------------+------------+
| year(now()) | month(now()) | day(now()) |
+-------------+--------------+------------+
|        2017 |            4 |          2 |
+-------------+--------------+------------+
1 row in set (0.00 sec)

6)获取系统日期时间中的月份、日

mysql> SELECT month(sysdate()),day(sysdate());
+------------------+----------------+
| month(sysdate()) | day(sysdate()) |
+------------------+----------------+
|                4 |              2 |
+------------------+----------------+
1 row in set (0.00 sec)

7)获取系统日期时间中的时刻

mysql> SELECT time(sysdate());
+-----------------+
| time(sysdate()) |
+-----------------+
| 04:06:08        |
+-----------------+
1 row in set (0.00 sec)