目录
1 案例1：构建MySQL服务器
1.1 问题
1.2 方案
1.3 步骤
2 案例2：密码管理
2.1 问题
2.2 步骤
3 案例3：安装图形软件
3.1 问题
3.2 方案
3.3 步骤
4 案例4：筛选条件
4.1 问题
4.2 方案
4.3 步骤
1 案例1：构建MySQL服务器
1.1 问题
- 在IP地址192.168.88.50主机和192.168.88.51主机上部署mysql服务
- 练习必备命令的使用
1.2 方案
准备2台虚拟机，要求如下：
配置yum源、关闭selinux和防火墙，如果忘记了请自行补习前边课程的知识或查看今天讲课的PPT,谢谢!!!
1.3 步骤
实现此案例需要按照如下步骤进行。
步骤一：安装软件
命令操作如下所示：
mysql-server 提供服务软件
mysql 提供命令软件
[root@mysql50 ~]# yum -y install mysql-server mysql //安装提供服务和命令软件//软件已安装[root@mysql50 ~]# rpm -q mysql-server mysqlmysql-server-8.0.26-1.module+el8.4.0+652+6de068a7.x86_64mysql-8.0.26-1.module+el8.4.0+652+6de068a7.x86_64[root@mysql50 ~]#[root@mysql50 ~]# rpm -qi mysql-server //查看软件信息Name : mysql-serverVersion : 8.0.26Release : 1.module+el8.4.0+652+6de068a7Architecture: x86_64Install Date: 2023年03月13日 星期一 12时09分38秒Group : UnspecifiedSize : 126674945License : GPLv2 with exceptions and LGPLv2 and BSDSignature : RSA/SHA256, 2021年09月22日 星期三 07时27分14秒, Key ID 15af5dac6d745a60Source RPM : mysql-8.0.26-1.module+el8.4.0+652+6de068a7.src.rpmBuild Date : 2021年09月22日 星期三 07时06分32秒Build Host : ord1-prod-x86build005.svc.aws.rockylinux.orgRelocations : (not relocatable)Packager : infrastructure@rockylinux.orgVendor : RockyURL : http://www.mysql.comSummary : The MySQL server and related filesDescription :MySQL is a multi-user, multi-threaded SQL database server. MySQL is aclient/server implementation consisting of a server daemon (mysqld)and many different client programs and libraries. This package containsthe MySQL server and some accompanying files and directories.[root@mysql50 ~]# systemctl start mysqld //启动服务[root@mysql50 ~]# systemctl enable mysqld //开机运行[root@mysql50 ~]# systemctl enable mysqld //设置服务开机运行Created symlink /etc/systemd/system/multi-user.target.wants/mysqld.service → /usr/lib/systemd/system/mysqld.service.步骤二：查看端口号和进程名
命令操作如下所示：
[root@mysql50 ~]# ps -C mysqld //仅查看mysqld进程PID TTY TIME CMD21912 ? 00:00:00 mysqld[root@mysql50 ~]#[root@mysql50 ~]# ss -utnlp | grep 3306 查看端口tcp LISTEN 0 70 *:33060 *:* users:(("mysqld",pid=21912,fd=22))tcp LISTEN 0 128 *:3306 *:* users:(("mysqld",pid=21912,fd=25))[root@mysql50 ~]# 或[root@mysql50 ~]# netstat -utnlp | grep mysqld //仅查看mysqld进程tcp6 0 0 :::33060 :::* LISTEN 21912/mysqld tcp6 0 0 :::3306 :::* LISTEN 21912/mysqld [root@mysql50 ~]#说明：
MySQL 8中的3306端口是MySQL服务默认使用的端口，主要用于建立客户端与MySQL服务器之间的连接。
MySQL 8中的33060端口是MySQL Shell默认使用的管理端口，主要用于执行各种数据库管理任务。远程管理MySQL服务器：使用MySQL Shell连接到MySQL服务，并在远程管理控制台上执行各种数据库管理操作，例如创建、删除、备份和恢复数据库等。
步骤三：连接服务。
说明： 数据库管理员本机登陆默认没有密码
命令操作如下所示：
[root@mysql50 ~]# mysql //连接服务Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 8Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> 登陆后的提示符mysql> exit //断开连接Bye[root@mysql50 ~]#步骤四：配置第2台数据库服务器MySQL51。
命令操作如下所示：
[root@mysql51 ~]# yum -y install mysql-server mysql[root@mysql51 ~]# systemctl start mysqld[root@mysql51 ~]# systemctl enable mysqld[root@mysql51 ~]# mysqlmysql> exitBye[root@mysql51 ~]#步骤五：练习必备命令的使用（在mysql50主机完成练习）
命令操作如下所示：
mysql> select version() ; //查看数据库软件版本+-----------+| version() |+-----------+| 8.0.26 |+-----------+1 row in set (0.00 sec)mysql> select user() ; //查看登陆的用户和客户端地址 +----------------+| user() |+----------------+| root@localhost | 管理员root本机登陆+----------------+1 row in set (0.00 sec) mysql> show databases; //查看已有的库+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys |+--------------------+4 rows in set (0.00 sec)mysql>说明：
默认4个库 不可以删除，存储的是 服务运行时加载的不同功能的程序和数据。
information_schema：是MySQL数据库提供的一个虚拟的数据库，存储了MySQL数据库中的相关信息，比如数据库、表、列、索引、权限、角色等信息。它并不存储实际的数据，而是提供了一些视图和存储过程，用于查询和管理数据库的元数据信息。
mysql：存储了MySQL服务器的系统配置、用户、账号和权限信息等。它是MySQL数据库最基本的库，存储了MySQL服务器的核心信息。
performance_schema：存储了MySQL数据库的性能指标、事件和统计信息等数据，可以用于性能分析和优化。
sys：是MySQL 8.0引入的一个新库，它基于information_schema和performance_schema视图，提供了更方便、更直观的方式来查询和管理MySQL数据库的元数据和性能数据。
mysql> select database(); //查看当前在那个库里 null 表示没有在任何库里+------------+| database() |+------------+| NULL |+------------+1 row in set (0.00 sec)mysql> use mysql ; //切换到mysql库mysql> select database(); // 再次显示所在的库+------------+| database() |+------------+| mysql |+------------+1 row in set (0.00 sec)mysql> show tables; //显示库里已有的表+------------------------------------------------------+| Tables_in_mysql |+------------------------------------------------------+| columns_priv || component || db || default_roles || engine_cost || func || general_log || global_grants || gtid_executed || help_category || help_keyword || help_relation || help_topic || innodb_index_stats || innodb_table_stats || password_history || plugin || procs_priv || proxies_priv || replication_asynchronous_connection_failover || replication_asynchronous_connection_failover_managed || replication_group_configuration_version || replication_group_member_actions || role_edges || 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 |+------------------------------------------------------+37 rows in set (0.00 sec)mysql> exit ; 断开连接Bye[root@mysql50 ~]# 2 案例2：密码管理
2.1 问题
1） 在192.168.88.50主机做如下练习：
- 设置root密码为tarena
- 修改root密码为123qqq…A
- 破解root密码为NSD2023…a
2.2 步骤
实现此案例需要按照如下步骤进行。
步骤一：设置root密码为tarena
命令操作如下所示：
2行输出是警告而已不用关心
[root@mysql50 ~]# mysqladmin -uroot -p password "tarena"Enter password: //敲回车mysqladmin: [Warning] Using a password on the command line interface can be insecure.Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.[root@mysql50 ~]# mysql //无密码连接被拒绝ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)[root@mysql50 ~]#[root@mysql50 ~]# mysql -uroot –ptarena //连接时输入密码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 14Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> 登陆成功步骤二：修改root密码为123qqq…A
命令操作如下所示：
[root@mysql50 ~]# mysqladmin -uroot -ptarena password "123qqq...A" //修改密码mysqladmin: [Warning] Using a password on the command line interface can be insecure.Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.[root@mysql50 ~]# mysql -uroot –ptarena //旧密码无法登陆mysql: [Warning] Using a password on the command line interface can be insecure.ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)[root@mysql50 ~]# mysql -uroot -p123qqq...A //新密码登陆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 18Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> 登陆成功步骤三：破解root密码为NSD2023…a
说明：在mysql50主机做此练习
命令操作如下所示：
[root@mysql50 ~]# mysql -uroot -pNSD2023...a //破解前登陆失败mysql: [Warning] Using a password on the command line interface can be insecure.ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)[root@mysql50 ~]# vim /etc/my.cnf.d/mysql-server.cnf //修改主配置文件[mysqld]skip-grant-tables //手动添加此行 作用登陆时不验证密码:wq[root@mysql50 ~]# systemctl restart mysqld //重启服务 作用让服务以新配置运行[root@mysql50 ~]# mysql //连接服务Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 7Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.//查看存放密码的表头名Mysql> desc mysql.user ;//把mysql库下user表中 用户root的密码设置为无；mysql> update mysql.user set authentication_string="" where user="root";Query OK, 1 row affected (0.05 sec)Rows matched: 1 Changed: 1 Warnings: 0mysql> exit; 断开连接Bye[root@mysql50 ~]# vim /etc/my.cnf.d/mysql-server.cnf 编辑配置文件[mysqld]#skip-grant-tables //注释添加的行:wq[root@mysql50 ~]# systemctl restart mysqld //重启服务 作用让注释生效[root@localhost ~]# mysql 无密码登陆Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 8Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.//设置root用户本机登陆密码mysql> alter user root@"localhost" identified by "NSD2023...a";Query OK, 0 rows affected (0.00 sec)mysql> exit 断开连接Bye[root@localhost ~]# mysql 不输密码无法登陆ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)[root@localhost ~]# mysql -uroot -pNSD2023...a 使用破解的密码登陆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 10Server version: 8.0.26 Source distributionCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql>mysql> 登陆成功mysql> show databases; 查看已有的库+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys |+--------------------+4 rows in set (0.01 sec)3 案例3：安装图形软件
3.1 问题
- 在IP地址192.168.88.50主机安装phpmyadmin软件
- 客户端通过访问phpmyadmin软件管理数据库
3.2 方案
把用到的软件拷贝的虚拟机mysql50里
在mysql50主机，首先配置运行环境LNP,然后安装phpmyadmin软件,最后打开真机的浏览器输入phpmyadmin的网址访问。
3.3 步骤
实现此案例需要按照如下步骤进行。
步骤一：部署运行环境LNP
命令操作如下所示：
gcc 源码包编译工具unzip 提供解压.zip 压缩包命令make 源码软件编译命令pcre-devel 支持正则表达式zlib-devel 提供数据压缩命令[root@mysql50 ~]# yum -y install gcc unzip make pcre-devel zlib-devel //安装依赖[root@mysql50 ~]# tar -xf nginx-1.22.1.tar.gz //解压源码[root@mysql50 ~]# cd nginx-1.22.1 //进源码目录[root@mysql50 nginx-1.22.1]# ./configure //配置[root@mysql50 nginx-1.22.1]# make && make install //编译并安装[root@mysql50 nginx-1.22.1]# ls /usr/local/nginx/ //查看安装目录conf html logs sbin[root@mysql50 nginx-1.22.1]# vim /usr/local/nginx/conf/nginx.conf //修改主配置文件43 location / {44 root html;45 index index.php index.html index.htm; //添加首页名46 }65 location ~ \.php$ { //访问.php的请求转给本机的9000端口66 root html;67 fastcgi_pass 127.0.0.1:9000;68 fastcgi_index index.php;69 #fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;70 include fastcgi.conf; //保存nginx变量文件71 }:wq[root@mysql50 nginx-1.22.1]# /usr/local/nginx/sbin/nginx //启动服务[root@mysql50 nginx-1.22.1]# netstat -utnlp | grep 80 //查看端口tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 42182/nginx: master [root@mysql50 nginx-1.22.1]#php 解释php代码php-devel php扩展包 php-mysqlnd 连接mysql命令包php-json 支持json代码php-fpm 提供fpm服务[root@mysql50 ~]# yum -y install php php-devel php-mysqlnd php-json php-fpm //安装php软件[root@mysql50 ~]# vim /etc/php-fpm.d/www.conf //修改主配置文件38 ;listen = /run/php-fpm/www.sock39 listen = 127.0.0.1:9000 //非socket方式运行,不是必须的:wq[root@mysql50 ~]# systemctl start php-fpm //启动服务[root@mysql50 ~]# netstat -utnlp | grep 9000 //查看端口tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN 67251/php-fpm: mast [root@mysql50 ~]#[root@mysql50 ~]# vim /usr/local/nginx/html/test.php //编写php脚本<?php$name = "plj" ;echo $name ;echo "\n" ;?>:wq[root@mysql50 ~]# curl http://localhost/test.php //访问脚本plj[root@mysql50 ~]#步骤二：安装phpmyadmin软件
命令操作如下所示：
[root@mysql50 ~]# unzip phpMyAdmin-5.2.1-all-languages.zip //解压[root@mysql50 ~]# mv phpMyAdmin-5.2.1-all-languages /usr/local/nginx/html/phpmyadmin //移动并改名 ，为了便于访问[root@mysql50 ~]# cd /usr/local/nginx/html/phpmyadmin/ //进软件目录[root@mysql50 phpmyadmin]# cp config.sample.inc.php config.inc.php //创建主配置文件[root@mysql50 phpmyadmin]# vim config.inc.php //修改主配置文件//定义cookies验证码16 $cfg['blowfish_secret'] = 'plj123'; /* YOU MUST FILL IN THIS FOR COOKIE AUTH! *///管理本机的数据库服务30 $cfg['Servers'][$i]['host'] = 'localhost';:wq[root@mysql50 phpmyadmin]# setenforce 0 //关闭selinux[root@mysql50 phpmyadmin]# systemctl stop firewalld //关闭防火墙步骤三：客户端访问
命令操作如下所示：
http://192.168.88.50/phpmyadmin 打开浏览器输入此网址 效果如图-1所示
说明：输入数据库管理员root 和 密码 成功后如图-2所示
4 案例4：筛选条件
4.1 问题
- 准备练习环境
- 练习数值比较
- 练习范围匹配
- 练习模糊匹配
- 练习正则匹配
- 练习逻辑比较
- 练习字符比较/空/非空
- 练习别名/去重/合并
4.2 方案
拷贝tarena.sql文件到mysql50主机里，然后使用tarena.sql创建练习使用的数据。
4.3 步骤
实现此案例需要按照如下步骤进行。
步骤一：准备练习环境
//拷贝tarena.sql 拷贝到 mysql50主机的/root 下[openeuler@server1 ~]$ scp /linux-soft/s3/tarena.sql root@192.168.88.50:/root/root@192.168.88.50's password: tarena.sql 100% 284KB 171.9MB/s 00:00 //连接mysql50主机 [openeuler@server1 ~]$ ssh root@192.168.88.50root@192.168.88.50's password: Last login: Tue May 23 10:59:57 2023 from 192.168.88.254//恢复数据[root@mysql50 ~]# mysql -uroot -pNSD2023...a < /root/tarena.sqlmysql: [Warning] Using a password on the command line interface can be insecure.//连接服务[root@mysql50 ~]# mysql -uroot -pNSD2023...amysql> show databases; //查看库+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys || tarena | 恢复的库+--------------------+5 rows in set (0.00 sec)mysql> use tarena; //进入库Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> show tables; //查看表+------------------+| Tables_in_tarena |+------------------+| departments | 部门表| employees | 员工表| salary | 工资表| user | 用户表+------------------+4 rows in set (0.00 sec)使用user 表做查询练习
user表里存储的是 系统用户信息( 就是 /etc/passwd 文件的内容)
mysql> desc tarena.user; //查看表头+----------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------+-------------+------+-----+---------+----------------+| id | int(11) | NO | PRI | NULL | auto_increment |行号| name | char(20) | YES | | NULL | |用户名| password | char(1) | YES | | NULL | |密码占位符| uid | int(11) | YES | | NULL | | uid号| gid | int(11) | YES | | NULL | | gid号| comment | varchar(50) | YES | | NULL | | 描述信息| homedir | varchar(80) | YES | | NULL | | 家目录| shell | char(30) | YES | | NULL | | 解释器+----------+-------------+------+-----+---------+----------------+8 rows in set (0.00 sec)elect命令格式演示
语法格式1 SELECT 字段列表 FROM 库名.表名;
语法格式2 SELECT 字段列表 FROM 库名.表名 where 筛选条件;
mysql> select name from tarena.user; //查看一个表头mysql> select name ,uid from tarena.user; //查看多个表头mysql> select * from tarena.user; //查看所有表头加筛选条件
mysql> select * from tarena.user where name = “root”; //查找root用户信息 +----+------+----------+------+------+---------+---------+-----------+| id | name | password | uid | gid | comment | homedir | shell |+----+------+----------+------+------+---------+---------+-----------+| 1 | root | x | 0 | 0 | root | /root | /bin/bash |+----+------+----------+------+------+---------+---------+-----------+1 row in set (0.00 sec)mysql> mysql> select * from tarena.user where id = 2 ; //查找第2行用户信息+----+------+----------+------+------+---------+---------+--------------+| id | name | password | uid | gid | comment | homedir | shell |+----+------+----------+------+------+---------+---------+--------------+| 2 | bin | x | 1 | 1 | bin | /bin | /sbin/nologin |+----+------+----------+------+------+---------+---------+--------------+1 row in set (0.00 sec)步骤二：练习数值比较
比较符号：
= != > >= < <=
相等 不相等 大于 大于等于 小于 小于等于
符号两边要是数字或数值类型的表头 符号左边与符号右边做比较
//查看第3行的行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where id = 3;+----+--------+------+------+| id | name | uid | gid |+----+--------+------+------+| 3 | daemon | 2 | 2 |+----+--------+------+------+1 row in set (0.00 sec)//查看前2行的行号用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where id < 3;+----+------+------+------+| id | name | uid | gid |+----+------+------+------+| 1 | root | 0 | 0 || 2 | bin | 1 | 1 |+----+------+------+------+2 rows in set (0.00 sec)//查看前3行的行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where id <= 3;+----+--------+------+------+| id | name | uid | gid |+----+--------+------+------+| 1 | root | 0 | 0 || 2 | bin | 1 | 1 || 3 | daemon | 2 | 2 |+----+--------+------+------+3 rows in set (0.00 sec)//查看前uid号大于6000的行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where uid > 6000;+----+-----------+-------+-------+| id | name | uid | gid |+----+-----------+-------+-------+| 22 | nfsnobody | 65534 | 65534 |+----+-----------+-------+-------+1 row in set (0.00 sec)//查看前uid号大于等于1000的行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where uid >= 1000;+----+-----------+-------+-------+| id | name | uid | gid |+----+-----------+-------+-------+| 22 | nfsnobody | 65534 | 65534 || 24 | plj | 1000 | 1000 |+----+-----------+-------+-------+2 rows in set (0.00 sec)//查看uid号和gid号相同的行 仅显示行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where uid = gid;+----+-----------------+-------+-------+| id | name | uid | gid |+----+-----------------+-------+-------+| 1 | root | 0 | 0 || 2 | bin | 1 | 1 || 3 | daemon | 2 | 2 || 13 | nobody | 99 | 99 || 14 | systemd-network | 192 | 192 || 15 | dbus | 81 | 81 || 17 | sshd | 74 | 74 || 18 | postfix | 89 | 89 || 20 | rpc | 32 | 32 || 21 | rpcuser | 29 | 29 || 22 | nfsnobody | 65534 | 65534 || 23 | haproxy | 188 | 188 || 24 | plj | 1000 | 1000 || 25 | apache | 48 | 48 || 26 | mysql | 27 | 27 |+----+-----------------+-------+-------+15 rows in set (0.00 sec)//查看uid号和gid号不一样的行 仅显示行号、用户名、uid、gid 四个表头的值mysql> select id,name,uid,gid from tarena.user where uid != gid;+----+----------+------+------+| id | name | uid | gid |+----+----------+------+------+| 4 | adm | 3 | 4 || 5 | lp | 4 | 7 || 6 | sync | 5 | 0 || 7 | shutdown | 6 | 0 || 8 | halt | 7 | 0 || 9 | mail | 8 | 12 || 10 | operator | 11 | 0 || 11 | games | 12 | 100 || 12 | ftp | 14 | 50 || 16 | polkitd | 999 | 998 || 19 | chrony | 998 | 996 |+----+----------+------+------+11 rows in set (0.00 sec)mysql>步骤三：练习范围匹配
in （值列表） //在…里
not in （值列表） //不在…里
between 数字1 and 数字2 //在…之间
命令操作如下所示：
//uid号表头的值 是 (1 , 3 , 5 , 7) 中的任意一个即可mysql> select name , uid from tarena.user where uid in (1 , 3 , 5 , 7); +------+------+| name | uid |+------+------+| bin | 1 || adm | 3 || sync | 5 || halt | 7 |+------+------+//shell 表头的的值 不是 "/bin/bash"或"/sbin/nologin" 即可mysql> select name , shell from tarena.user where shell not in ("/bin/bash","/sbin/nologin");+----------+----------------+| name | shell |+----------+----------------+| sync | /bin/sync || shutdown | /sbin/shutdown || halt | /sbin/halt || mysql | /bin/false |+----------+----------------+//id表头的值 在 10 到 20 之间即可 包括 10 和 20 本身mysql> select id , name , uid from tarena.user where id between 10 and 20 ;+----+-----------------+------+| id | name | uid |+----+-----------------+------+| 10 | operator | 11 || 11 | games | 12 || 12 | ftp | 14 || 13 | nobody | 99 || 14 | systemd-network | 192 || 15 | dbus | 81 || 16 | polkitd | 999 || 17 | sshd | 74 || 18 | postfix | 89 || 19 | chrony | 998 || 20 | rpc | 32 |+----+-----------------+------+11 rows in set (0.00 sec)mysql> 步骤四：练习模糊匹配
where 字段名 like "表达式";
通配符
_ 表示 1个字符
% 表示零个或多个字符
命令操作如下所示：
//找名字必须是3个字符的 （没有空格挨着敲）mysql> select name from tarena.user where name like "___"; +------+| name |+------+| bin || adm || ftp || rpc || plj || bob |+------+6 rows in set (0.00 sec)//找名字必须是4个字符的（没有空格挨着敲）mysql> select name from tarena.user where name like "_ _ _ _"; +------+| name |+------+| root || sync || halt || mail || dbus || sshd || null |+------+7 rows in set (0.00 sec)//找名字以字母a开头的（没有空格挨着敲）mysql> select name from tarena.user where name like "a%"; //查找名字至少是4个字符的表达式mysql> select name from tarena.user where name like "%_ _ _ _%";（没有空格挨着敲）mysql> select name from tarena.user where name like "_ _%_ _";（没有空格挨着敲）mysql> select name from tarena.user where name like "_ _ _ _%";（没有空格挨着敲）步骤五：练习正则匹配
格式：select 字段名列表 from 库名.表名 where字段名 regexp '正则表达式'；
回顾shell课程学过的元字符(正则符号)
^ 匹配行首
$ 匹配行尾
[] 匹配范围内任意一个
* 前边的表达式出现零次或多次
| 或者
. 任意一个字符
命令操作如下所示：
//添加有数字的名字insert into tarena.user(name)values("yaya9");insert into tarena.user(name)values("6yaya");insert into tarena.user(name)values("ya7ya");insert into tarena.user(name)values("yay8a");//查看名字里有数字的mysql> select name from tarena.user where name regexp "[0-9]"; +-------+| name |+-------+| yaya9 || 6yaya || ya7ya || yay8a |+-------+4 rows in set (0.00 sec)//查看名字以数字开头mysql> select name from tarena.user where name regexp "^[0-9]"; +-------+| name |+-------+| 6yaya |+-------+1 row in set (0.00 sec)//查看名字以数字结尾mysql> select name from tarena.user where name regexp "[0-9]$"; +-------+| name |+-------+| yaya9 |+-------+1 row in set (0.00 sec)mysql> //查看名字以r开头mysql> select name from tarena.user where name regexp "^r"; +---------+| name |+---------+| root || rpc || rpcuser |+---------+3 rows in set (0.00 sec)//查看名字以t结尾mysql> select name from tarena.user where name regexp "t$"; +------+| name |+------+| root || halt |+------+2 rows in set (0.00 sec)mysql> //查看名字以r开头或t结尾mysql> select name from tarena.user where name regexp "^r|t$"; +---------+| name |+---------+| root || halt || rpc || rpcuser |+---------+4 rows in set (0.00 sec)//名字r开头t结尾mysql> select name from tarena.user where name regexp "^r.*t$"; +------+| name |+------+| root |+------+1 row in set (0.00 sec)mysql> 步骤六：练习逻辑比较
多个判断条件
逻辑与 and （&&） 多个判断条件必须同时成立
逻辑或 or （||） 多个判断条件其中某个条件成立即可
逻辑非 not （!） 取反
命令操作如下所示：
//逻辑非例子，查看解释器不是/bin/bash 的mysql> select name,shell from tarena.user where shell != "/bin/bash"; //not 也是取反 要放在表达式的前边mysql> select name,shell from tarena.user where not shell = "/bin/bash";//id值不在 10 到 20 之间 mysql> select id , name from tarena.user where not id between 10 and 20 ; //逻辑与 例子mysql> select name , uid from tarena.user where name="root" and uid = 1; Empty set (0.00 sec)mysql> select name , uid from tarena.user where name="root" and uid = 0;+------+------+| name | uid |+------+------+| root | 0 |+------+------+1 row in set (0.00 sec)//逻辑或 例子mysql> select name , uid from tarena.user where name = "root" or name = "bin" or uid = 1;+------+------+| name | uid |+------+------+| root | 0 || bin | 1 |+------+------+mysql>() 提高优先级
mysql> select 2 + 3 * 5 ; //使用默认计算顺序 先乘除后加减+------------+| 2 + 3 * 5 |+------------+| 17 |+------------+1 row in set (0.00 sec)mysql> select (2 + 3 ) * 5 ; //先加法再乘法+---------------+| (2 + 3 ) * 5 |+---------------+| 25 |+---------------+1 row in set (0.00 sec)mysql>逻辑匹配什么时候需要加（）
逻辑与and 优先级高于逻辑或 or
如果在筛选条件里既有and 又有 or 默认先判断and 再判断or
//没加（） 的查询结果select name , uid from tarena.user where name = "root" or name = "bin" and uid = 1 ; +------+------+| name | uid |+------+------+| root | 0 || bin | 1 |+------+------+2 rows in set (0.00 sec)//加（）的查询结果select name , uid from tarena.user where (name = "root" or name = "bin") and uid = 1 ; +------+------+| name | uid |+------+------+| bin | 1 |+------+------+1 row in set (0.00 sec)mysql>步骤七：练习字符比较/空/非空
符号两边必须是字符 或字符类型的表头
= 相等比较
!= 不相等比较。
命令操作如下所示：
//查看表里是否有名字叫apache的用户mysql> select name from tarena.user where name="apache" ;+--------+| name |+--------+| apache |+--------+1 row in set (0.00 sec)//输出解释器不是/bin/bash的用户名 及使用的解释器mysql> select name , shell from tarena.user where shell != "/bin/bash";+-----------------+----------------+| name | shell |+-----------------+----------------+| bin | /sbin/nologin || daemon | /sbin/nologin || adm | /sbin/nologin || lp | /sbin/nologin || sync | /bin/sync || shutdown | /sbin/shutdown || halt | /sbin/halt || mail | /sbin/nologin || operator | /sbin/nologin || games | /sbin/nologin || ftp | /sbin/nologin || nobody | /sbin/nologin || systemd-network | /sbin/nologin || dbus | /sbin/nologin || polkitd | /sbin/nologin || sshd | /sbin/nologin || postfix | /sbin/nologin || chrony | /sbin/nologin || rpc | /sbin/nologin || rpcuser | /sbin/nologin || nfsnobody | /sbin/nologin || haproxy | /sbin/nologin || apache | /sbin/nologin || mysql | /bin/false |+-----------------+----------------+24 rows in set (0.00 sec)mysql>空 is null 表头下没有数据
非空 is not null 表头下有数据
mysql服务 使用关键字 null 或 NULL 表示表头没有数据
//添加新行 仅给行中的id 表头和name表头赋值mysql> insert into tarena.user(id,name) values(71,""); //零个字符mysql> insert into tarena.user(id,name) values(72,"null");//普通字母mysql> insert into tarena.user(id,name) values(73,NULL); //表示空mysql> insert into tarena.user(id,name) values(74,null); //表示空//查看id表头值大于等于70 的行 仅显示行中 id表头 和 name 表头的值mysql> select id , name from tarena.user where id >= 71;+----+------+| id | name |+----+------+| 71 | || 72 | null || 73 | NULL || 74 | NULL |+----+------+//查看name 表头没有数据的行 仅显示行中id表头 和 naeme 表头的值mysql> select id , name from tarena.user where name is null;+----+------+| id | name |+----+------+| 28 | NULL || 29 | NULL || 73 | NULL || 74 | NULL |+----+------+//查看name 表头是0个字符的行， 仅显示行中id表头 和 naeme 表头的值mysql> select id , name from tarena.user where name="";+----+------+| id | name |+----+------+| 71 | |+----+------+1 row in set (0.00 sec)//查看name 表头值是null的行， 仅显示行中id表头 和 naeme 表头的值mysql> select id , name from tarena.user where name="null";+----+------+| id | name |+----+------+| 72 | null |+----+------+1 row in set (0.00 sec)//查看name 表头有数据的行， 仅显示行中id表头 和 name 表头的值mysql> select id , name from tarena.user where name is not null;+----+-----------------+| id | name |+----+-----------------+| 1 | root || 2 | bin || 3 | daemon || 4 | adm || 5 | lp |........| 27 | bob || 71 | || 72 | null |+----+-----------------+步骤八：练习别名/去重/合并
命令操作如下所示：
//定义别名使用 as 或 空格 mysql> select name , homedir from tarena.user;mysql> select name as 用户名 , homedir 家目录 from tarena.user;//拼接 concat()mysql> select concat(name,"-",uid) as 用户信息 from tarena.user where uid <= 5;+--------------+| 用户信息 |+--------------+| root-0 || bin-1 || daemon-2 || adm-3 || lp-4 || sync-5 |+--------------+6 rows in set (0.00 sec)//2列拼接mysql> select concat(name , "-" , uid) as 用户信息 from tarena.user where uid <= 5;//多列拼接mysql> select concat(name , "-" , uid , "-" , gid) as 用户信息 from tarena.user where uid <= 5;+--------------+| 用户信息 |+--------------+| root-0-0 || bin-1-1 || daemon-2-2 || adm-3-4 || lp-4-7 || sync-5-0 |+--------------+去重显示 distinct 字段名列表
//去重前输出mysql> select shell from tarena.user where shell in ("/bin/bash","/sbin/nologin") ;+---------------+| shell |+---------------+| /bin/bash || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /sbin/nologin || /bin/bash || /sbin/nologin |+---------------+22 rows in set (0.00 sec)//去重后查看mysql> select distinct shell from tarena.user where shell in ("/bin/bash","/sbin/nologin") ;+---------------+| shell |+---------------+| /bin/bash || /sbin/nologin |+---------------+2 rows in set (0.01 sec)mysql>
