mysql进阶

1.安装mysql

1.1 mysql二进制安装

 #创建mysql用户
[root@zzd139 ~]# useradd -Mrs /sbin/nologin mysql
 
#安装ncurses-compat-libs
[root@zzd139 ~]# dnf -y install ncurses-compat-libs
 
#将mysql二进制包解压到/usr/local/目录下
[root@zzd139 ~]# tar xf mysql-5.7.38-linux-glibc2.12-x86_64.tar.gz -C /usr/local/
[root@zzd139 local]# ln -sv mysql-5.7.38-linux-glibc2.12-x86_64/ mysql
'mysql' -> 'mysql-5.7.38-linux-glibc2.12-x86_64/'
[root@zzd139 local]# ll
total 0
drwxr-xr-x. 2 root root   6 May 19  2020 bin
drwxr-xr-x. 2 root root   6 May 19  2020 etc
drwxr-xr-x. 2 root root   6 May 19  2020 games
drwxr-xr-x. 2 root root   6 May 19  2020 include
drwxr-xr-x. 2 root root   6 May 19  2020 lib
drwxr-xr-x. 3 root root  17 Jun 28 09:25 lib64
drwxr-xr-x. 2 root root   6 May 19  2020 libexec
lrwxrwxrwx. 1 root root  36 Jul 27 16:54 mysql -> mysql-5.7.38-linux-glibc2.12-x86_64/
drwxr-xr-x. 9 root root 129 Jul 27 16:53 mysql-5.7.38-linux-glibc2.12-x86_64
drwxr-xr-x. 2 root root   6 May 19  2020 sbin
drwxr-xr-x. 5 root root  49 Jun 28 09:25 share
drwxr-xr-x. 2 root root   6 May 19  2020 src
[root@zzd139 local]# cd mysql
[root@zzd139 mysql]# ls
bin  docs  include  lib  LICENSE  man  README  share  support-files
 
#修改目录/usr/local/mysql的属主属组
[root@zzd139 mysql]# chown -R mysql.mysql /usr/local/mysql
[root@zzd139 mysql]# chown -R mysql.mysql /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/
[root@zzd139 mysql]# ll -d /usr/local/mysql
lrwxrwxrwx. 1 mysql mysql 36 Jul 27 16:54 /usr/local/mysql -> mysql-5.7.38-linux-glibc2.12-x86_64/
[root@zzd139 mysql]# ll -d /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/
drwxr-xr-x. 9 mysql mysql 129 Jul 27 16:53 /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/
 
#配置mysql全局环境变量
[root@zzd139 mysql]# echo "export PATH=$PATH:/usr/local/mysql/bin" > /etc/profile.d/mysql.sh
[root@zzd139 mysql]# source /etc/profile.d/mysql.sh 
[root@zzd139 mysql]# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin:/usr/local/mysql/bin
 
#将mysql头文件添加至系统默认识别的目录/usr/include
[root@zzd139 mysql]# ln -sv /usr/local/mysql/include/ /usr/include/mysql
'/usr/include/mysql' -> '/usr/local/mysql/include/'
[root@zzd139 mysql]# ll -d /usr/include/mysql
lrwxrwxrwx. 1 root root 25 Jul 27 16:58 /usr/include/mysql -> /usr/local/mysql/include/
 
#将mysql的lib库文件添加到系统识别文件
[root@zzd139 mysql]# echo "/usr/local/mysql/lib/" > /etc/ld.so.conf.d/mysql.conf
[root@zzd139 mysql]# ldconfig 
 
#添加man文档
[root@zzd139 mysql]# vim /etc/man_db.conf 
$(添加如下内容)
	MANDATORY_MANPATH                       /usr/local/mysql/man
 
#建立存放数据目录
[root@zzd139 mysql]# mkdir -p /opt/mysql/data
[root@zzd139 mysql]# chown  -R mysql.mysql /opt/mysql/
[root@zzd139 mysql]# ll /opt/mysql/
total 0
drwxr-xr-x. 2 mysql mysql 6 Jul 27 17:06 data
 
#初始化数据库
[root@zzd139 ~]# mysqld --initialize --user=mysql --datadir=/opt/mysql/data
2022-07-27T09:09:13.223427Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2022-07-27T09:09:13.386290Z 0 [Warning] InnoDB: New log files created, LSN=45790
2022-07-27T09:09:13.429221Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2022-07-27T09:09:13.485193Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: c8900af2-0d8b-11ed-b3bc-000c29f177ce.
2022-07-27T09:09:13.485726Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2022-07-27T09:09:13.674856Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
2022-07-27T09:09:13.674870Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
2022-07-27T09:09:13.675192Z 0 [Warning] CA certificate ca.pem is self signed.
2022-07-27T09:09:13.746758Z 1 [Note] A temporary password is generated for root@localhost: oGDSXemN0u=f
#oGDSXemN0u=f就是mysql的密码，每次初始化密码都不一样，所以登录后首先修改密码，我们先将这个密码保存起来以防忘记
[root@zzd139 ~]# echo oGDSXemN0u=f > pass
[root@zzd139 ~]# cat pass 
oGDSXemN0u=f
 
#生成配置文件
[root@zzd139 ~]# vim /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/mysql/data
socket = /tmp/mysql.sock
port = 3306
pid-file = /opt/mysql/data/mysql.pid
user = mysql
skip-name-resolve
sql-mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
[root@zzd139 system]# chown -R mysql.mysql /etc/my.cnf
 
#启动mysql
[root@zzd139 ~]# /usr/local/mysql/support-files/mysql.server start
Starting MySQL.Logging to '/opt/mysql/data/zzd139.err'.
 SUCCESS! 
#关闭mysql
[root@zzd139 ~]# /usr/local/mysql/support-files/mysql.server stop
Shutting down MySQL.. SUCCESS! 
 
#使用systemd风格管理mysql服务
[root@zzd139 ~]# cd /usr/lib/systemd/system
[root@zzd139 system]# cp sshd.service mysqld.service
[root@zzd139 system]# vim mysqld.service 
    [Unit]
    Description=mysql server daemon
    After=network.target sshd-keygen.target
 
    [Service]
    Type=forking
    ExecStart=/usr/local/mysql/support-files/mysql.server start
    ExecStop=/usr/local/mysql/support-files/mysql.server stop
    ExecReload=/bin/kill -HUP $MAINPID
 
    [Install]
    WantedBy=multi-user.target
[root@zzd139 system]# systemctl daemon-reload 
[root@zzd139 system]# setenforce 0
$(这里还需要设置防火墙规则允许3306端口通过，觉得麻烦的话可以直接关闭防火墙)
[root@zzd139 system]# systemctl start mysqld.service
[root@zzd139 system]# systemctl status mysqld.service 
● mysqld.service - mysql server daemon
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2022-07-27 17:29:52 CST; 2min 1s ago
  Process: 3261 ExecStart=/usr/local/mysql/support-files/mysql.server start (code=exited, status=0/SUCCESS)
 Main PID: 3274 (mysqld_safe)
    Tasks: 28 (limit: 5770)
   Memory: 173.4M
   CGroup: /system.slice/mysqld.service
           ├─3274 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/opt/mysql/data --pid-file=/opt/mysql/data/mysql.pid
           └─3476 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/opt/mysql/data --plugin-dir=/usr/local/mysql/lib/plugi>
 
Jul 27 17:29:51 zzd139 systemd[1]: Starting mysql server daemon...
Jul 27 17:29:52 zzd139 mysql.server[3261]: Starting MySQL. SUCCESS!
Jul 27 17:29:52 zzd139 systemd[1]: Started mysql server daemon.
[root@zzd139 system]# ss -antl
State           Recv-Q          Send-Q                   Local Address:Port                    Peer Address:Port          Process          
LISTEN          0               128                            0.0.0.0:111                          0.0.0.0:*                              
LISTEN          0               128                            0.0.0.0:22                           0.0.0.0:*                              
LISTEN          0               80                                   *:3306                               *:*                              
LISTEN          0               128                               [::]:111                             [::]:*                              
LISTEN          0               128                               [::]:22                              [::]:*          
 
#登录mysql修改密码
$(使用初始化时的临时密码)
[root@zzd139 ~]# mysql -uroot -poGDSXemN0u=f
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 3
Server version: 5.7.38
 
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
 
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.
 
#使用下列sql语句修改密码
mysql> set password = password('xxxx');	$(括号里为密码)
Query OK, 0 rows affected, 1 warning (0.00 sec)

在登录mysql的时候可能会遇到报错

 mysql: error while loading shared libraries: libncurses.so.5: cannot open shared object file: No such file or directory

这个问题是因为缺少libncurses.so.5

 [root@zzd139 ~]# dnf provides libncurses.so.5
Last metadata expiration check: 8:00:13 ago on Wed 27 Jul 2022 09:35:30 AM CST.
ncurses-compat-libs-6.1-9.20180224.el8.i686 : Ncurses compatibility libraries
Repo        : BaseOS
Matched from:
Provide    : libncurses.so.5
 
#安装ncurses-compat-libs包即可
[root@zzd139 ~]# dnf -y install ncurses-compat-libs

1.2 mysql破解密码

如果不小心忘了mysql的密码，可以使用密码破解

 #修改mysql配置文件
[root@zzd139 ~]# vim /etc/my.cnf
$(添加如下内容)
	skip-grant-tables
#重启mysql服务
[root@zzd139 ~]# systemctl restart mysqld.service 
#登录mysql
[root@zzd139 ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.38 MySQL Community Server (GPL)
 
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
 
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> 
 
#修改mysql的root用户密码
mysql> update mysql.user set authentication_string = password('xxxxxx') where User = 'root' and Host = 'localhost';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1
 
#再次修改my.cnf文件
	$(删除或注释如下内容)
	skip-grant-tables
#重启mysql
[root@zzd139 ~]# systemctl restart mysqld.service

2.mysql配置文件

mysql配置文件为/etc/my.cnf

配置文件查找次序：若在多个配置文件中均有设定，则最后找到的最终生效

 /etc/my.cnf --> /etc/mysql/my.cnf --> --default-extra-file=/PATH/TO/CONF_FILE --> ~/.my.cnf

mysql常用配置文件参数：

参数	说明
port = 3306	设置监听端口
socket = /tmp/mysql.sock	指定套接字文件位置
basedir = /usr/local/mysql	指定MySQL的安装路径
datadir = /opt/mysql/data	指定MySQL的数据存放路径
pid-file = /opt/mysql/data/mysql.pid	指定进程ID文件存放路径
user = mysql	指定MySQL以什么用户的身份提供服务
skip-name-resolve	禁止MySQL对外部连接进行DNS解析使用这一选项可以消除MySQL进行DNS解析的时间。若开启该选项，则所有远程主机连接授权都要使用IP地址方式否则MySQL将无法正常处理连接请求

3.多表联查

3.1 什么是多表联查

前面所讲的查询语句都是针对一个表的，但是在关系型数据库中，表与表之间是有联系的，所以在实际应用中，经常使用多表查询。多表查询就是同时查询两个或两个以上的表。
在 MySQL 中，多表查询主要有交叉连接、内连接、外连接、分组查询与子查询等5种。

3.2 交叉连接(CROSS JOIN)

3.2.1 笛卡尔积

交叉连接(CROSS JOIN)：有两种，显式的和隐式的2种，一般用来返回连接表的笛卡尔积。
笛卡尔积（Cartesian product）是指两个集合 X 和 Y 的乘积。
例如，有 A 和 B 两个集合，它们的值如下：

 A = {1,2}
B = {3,4,5}

集合 A×B 和 B×A 的结果集分别表示为：

 A×B={(1,3), (1,4), (1,5), (2,3), (2,4), (2,5) };
B×A={(3,1), (3,2), (4,1), (4,2), (5,1), (5,2) };

以上 A×B 和 B×A 的结果就叫做两个集合的笛卡尔积。

并且，从以上结果我们可以看出：

两个集合相乘，不满足交换率，即 A×B≠B×A。
A 集合和 B 集合的笛卡尔积是 A 集合的元素个数 × B 集合的元素个数。

多表查询遵循的算法就是以上提到的笛卡尔积，表与表之间的连接可以看成是在做乘法运算。在实际应用中，应避免使用笛卡尔积，因为笛卡尔积中容易存在大量的不合理数据，简单来说就是容易导致查询结果重复、混乱。

3.2.2 交叉连接

交叉连接的语法格式如下

 SELECT <字段名> FROM <表1> CROSS JOIN <表2> [WHERE子句];

或

 SELECT <字段名> FROM <表1>, <表2> [WHERE子句];

注意：多个表交叉连接时，在 FROM 后连续使用 CROSS JOIN 或,即可。以上两种语法的返回结果是相同的，但是第一种语法才是官方建议的标准写法。

当连接的表之间没有关系时，我们会省略掉 WHERE 子句，这时返回结果就是两个表的笛卡尔积，返回结果数量就是两个表的数据行相乘。需要注意的是，如果每个表有 1000 行，那么返回结果的数量就有 1000×1000 = 1000000 行，数据量是非常巨大的。

交叉连接可以查询两个或两个以上的表，为了更好的理解，我们就讲解两个表的交叉连接查询。

查询学生信息表和科目信息表，并得到一个笛卡尔积。

为了方便观察学生信息表和科目表交叉连接后的运行结果，我们先分别查询出这两个表的数据，再进行交叉连接查询。

1.查询 tb_students_info 表中的数据，SQL 语句和运行结果如下：

 #创建数据库zzd
mysql> create database zzd;
Query OK, 1 row affected (0.01 sec)
 
#创建tb_students_info表
mysql> use zzd;
Database changed
mysql> create table tb_students_info(id int not null primary key auto_increment,name varchar(50),age tinyint,height float,course_id int);
Query OK, 0 rows affected (0.00 sec)
 
mysql> desc tb_students_info;
+-----------+-------------+------+-----+---------+----------------+
| Field     | Type        | Null | Key | Default | Extra          |
+-----------+-------------+------+-----+---------+----------------+
| id        | int(11)     | NO   | PRI | NULL    | auto_increment |
| name      | varchar(50) | YES  |     | NULL    |                |
| age       | tinyint(4)  | YES  |     | NULL    |                |
| height    | float       | YES  |     | NULL    |                |
| course_id | int(11)     | YES  |     | NULL    |                |
+-----------+-------------+------+-----+---------+----------------+
5 rows in set (0.02 sec)
 
#插入数据
mysql> insert into tb_students_info(name,age,height,course_id) values('Dany',25,160,1),('Green',23,158,2),('Henry',23,185,1),('Jane',22,162,,3),('Jim',24,175,2),('John',21,172,4),('Lily',22,165,4),('Susan',23,170,5),('Thomas',22,178,5),('Tom',23,165,5);
Query OK, 10 rows affected (0.00 sec)
Records: 10  Duplicates: 0  Warnings: 0
 
#查询表tb_students_info的记录
mysql> select * from tb_students_info;
+----+--------+------+--------+-----------+
| id | name   | age  | height | course_id |
+----+--------+------+--------+-----------+
|  1 | Dany   |   25 |    160 |         1 |
|  2 | Green  |   23 |    158 |         2 |
|  3 | Henry  |   23 |    185 |         1 |
|  4 | Jane   |   22 |    162 |         3 |
|  5 | Jim    |   24 |    175 |         2 |
|  6 | John   |   21 |    172 |         4 |
|  7 | Lily   |   22 |    165 |         4 |
|  8 | Susan  |   23 |    170 |         5 |
|  9 | Thomas |   22 |    178 |         5 |
| 10 | Tom    |   23 |    165 |         5 |
+----+--------+------+--------+-----------+
10 rows in set (0.00 sec)

2.查询 tb_course 表中的数据，SQL 语句和运行结果如下

 #创建tb_course表
mysql> create table tb_course(id int not null primary key auto_increment,course_name varchar(50));
Query OK, 0 rows affected (0.00 sec)
 
mysql> desc tb_course;
+-------------+-------------+------+-----+---------+----------------+
| Field       | Type        | Null | Key | Default | Extra          |
+-------------+-------------+------+-----+---------+----------------+
| id          | int(11)     | NO   | PRI | NULL    | auto_increment |
| course_name | varchar(50) | YES  |     | NULL    |                |
+-------------+-------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
 
#插入数据
mysql> insert into tb_course(course_name) values('Java'),('MySQL'),('Python'),('Go'),('C++');
Query OK, 5 rows affected (0.00 sec)
Records: 5  Duplicates: 0  Warnings: 0
 
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
+----+-------------+
5 rows in set (0.00 sec)

3.用 CROSS JOIN 查询出两张表中的笛卡尔积，SQL 语句和运行结果如下：

 mysql> select * from tb_course cross join tb_students_info;
+----+-------------+----+--------+------+--------+-----------+
| id | course_name | id | name   | age  | height | course_id |
+----+-------------+----+--------+------+--------+-----------+
|  1 | Java        |  1 | Dany   |   25 |    160 |         1 |
|  2 | MySQL       |  1 | Dany   |   25 |    160 |         1 |
|  3 | Python      |  1 | Dany   |   25 |    160 |         1 |
|  4 | Go          |  1 | Dany   |   25 |    160 |         1 |
|  5 | C++         |  1 | Dany   |   25 |    160 |         1 |
|  1 | Java        |  2 | Green  |   23 |    158 |         2 |
|  2 | MySQL       |  2 | Green  |   23 |    158 |         2 |
|  3 | Python      |  2 | Green  |   23 |    158 |         2 |
|  4 | Go          |  2 | Green  |   23 |    158 |         2 |
|  5 | C++         |  2 | Green  |   23 |    158 |         2 |
|  1 | Java        |  3 | Henry  |   23 |    185 |         1 |
|  2 | MySQL       |  3 | Henry  |   23 |    185 |         1 |
|  3 | Python      |  3 | Henry  |   23 |    185 |         1 |
|  4 | Go          |  3 | Henry  |   23 |    185 |         1 |
|  5 | C++         |  3 | Henry  |   23 |    185 |         1 |
|  1 | Java        |  4 | Jane   |   22 |    162 |         3 |
|  2 | MySQL       |  4 | Jane   |   22 |    162 |         3 |
|  3 | Python      |  4 | Jane   |   22 |    162 |         3 |
|  4 | Go          |  4 | Jane   |   22 |    162 |         3 |
|  5 | C++         |  4 | Jane   |   22 |    162 |         3 |
|  1 | Java        |  5 | Jim    |   24 |    175 |         2 |
|  2 | MySQL       |  5 | Jim    |   24 |    175 |         2 |
|  3 | Python      |  5 | Jim    |   24 |    175 |         2 |
|  4 | Go          |  5 | Jim    |   24 |    175 |         2 |
|  5 | C++         |  5 | Jim    |   24 |    175 |         2 |
|  1 | Java        |  6 | John   |   21 |    172 |         4 |
|  2 | MySQL       |  6 | John   |   21 |    172 |         4 |
|  3 | Python      |  6 | John   |   21 |    172 |         4 |
|  4 | Go          |  6 | John   |   21 |    172 |         4 |
|  5 | C++         |  6 | John   |   21 |    172 |         4 |
|  1 | Java        |  7 | Lily   |   22 |    165 |         4 |
|  2 | MySQL       |  7 | Lily   |   22 |    165 |         4 |
|  3 | Python      |  7 | Lily   |   22 |    165 |         4 |
|  4 | Go          |  7 | Lily   |   22 |    165 |         4 |
|  5 | C++         |  7 | Lily   |   22 |    165 |         4 |
|  1 | Java        |  8 | Susan  |   23 |    170 |         5 |
|  2 | MySQL       |  8 | Susan  |   23 |    170 |         5 |
|  3 | Python      |  8 | Susan  |   23 |    170 |         5 |
|  4 | Go          |  8 | Susan  |   23 |    170 |         5 |
|  5 | C++         |  8 | Susan  |   23 |    170 |         5 |
|  1 | Java        |  9 | Thomas |   22 |    178 |         5 |
|  2 | MySQL       |  9 | Thomas |   22 |    178 |         5 |
|  3 | Python      |  9 | Thomas |   22 |    178 |         5 |
|  4 | Go          |  9 | Thomas |   22 |    178 |         5 |
|  5 | C++         |  9 | Thomas |   22 |    178 |         5 |
|  1 | Java        | 10 | Tom    |   23 |    165 |         5 |
|  2 | MySQL       | 10 | Tom    |   23 |    165 |         5 |
|  3 | Python      | 10 | Tom    |   23 |    165 |         5 |
|  4 | Go          | 10 | Tom    |   23 |    165 |         5 |
|  5 | C++         | 10 | Tom    |   23 |    165 |         5 |
+----+-------------+----+--------+------+--------+-----------+
50 rows in set (0.00 sec)

由运行结果可以看出，tb_course 和 tb_students_info 表交叉连接查询后，返回了 50 条记录。可以想象，当表中的数据较多时，得到的运行结果会非常长，而且得到的运行结果也没太大的意义。所以，通过交叉连接的方式进行多表查询的这种方法并不常用，我们应该尽量避免这种查询。

 #查询 tb_course 表中的 id 字段和 tb_students_info 表中的 course_id 字段相等的内容
mysql> select * from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id;
+----+-------------+----+--------+------+--------+-----------+
| id | course_name | id | name   | age  | height | course_id |
+----+-------------+----+--------+------+--------+-----------+
|  1 | Java        |  1 | Dany   |   25 |    160 |         1 |
|  2 | MySQL       |  2 | Green  |   23 |    158 |         2 |
|  1 | Java        |  3 | Henry  |   23 |    185 |         1 |
|  3 | Python      |  4 | Jane   |   22 |    162 |         3 |
|  2 | MySQL       |  5 | Jim    |   24 |    175 |         2 |
|  4 | Go          |  6 | John   |   21 |    172 |         4 |
|  4 | Go          |  7 | Lily   |   22 |    165 |         4 |
|  5 | C++         |  8 | Susan  |   23 |    170 |         5 |
|  5 | C++         |  9 | Thomas |   22 |    178 |         5 |
|  5 | C++         | 10 | Tom    |   23 |    165 |         5 |
+----+-------------+----+--------+------+--------+-----------+
10 rows in set (0.00 sec)
 
#查询 tb_course 表中的 id 字段和 tb_students_info 表中的 course_id 字段相等的内容,不显示tb_course表的id字段
mysql> select tb_course.course_name,tb_students_info.* from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id;
+-------------+----+--------+------+--------+-----------+
| course_name | id | name   | age  | height | course_id |
+-------------+----+--------+------+--------+-----------+
| Java        |  1 | Dany   |   25 |    160 |         1 |
| MySQL       |  2 | Green  |   23 |    158 |         2 |
| Java        |  3 | Henry  |   23 |    185 |         1 |
| Python      |  4 | Jane   |   22 |    162 |         3 |
| MySQL       |  5 | Jim    |   24 |    175 |         2 |
| Go          |  6 | John   |   21 |    172 |         4 |
| Go          |  7 | Lily   |   22 |    165 |         4 |
| C++         |  8 | Susan  |   23 |    170 |         5 |
| C++         |  9 | Thomas |   22 |    178 |         5 |
| C++         | 10 | Tom    |   23 |    165 |         5 |
+-------------+----+--------+------+--------+-----------+
10 rows in set (0.00 sec)
 
#把两个表交叉查询，只查询学习java的学生信息
mysql> select tb_course.course_name,tb_students_info.* from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id and tb_course.course_name = 'Java';
+-------------+----+-------+------+--------+-----------+
| course_name | id | name  | age  | height | course_id |
+-------------+----+-------+------+--------+-----------+
| Java        |  1 | Dany  |   25 |    160 |         1 |
| Java        |  3 | Henry |   23 |    185 |         1 |
+-------------+----+-------+------+--------+-----------+
2 rows in set (0.00 sec)
 
#查看学习java的学生的身高
mysql> select tb_course.course_name,tb_students_info.height from tb_course cross join tb_students_info where tb_course.id = tb_students_infoo.course_id and tb_course.course_name = 'Java';
+-------------+--------+
| course_name | height |
+-------------+--------+
| Java        |    160 |
| Java        |    185 |
+-------------+--------+
2 rows in set (0.00 sec)
 
#查看学习java的学生的平均升高
mysql> select tb_course.course_name,avg(tb_students_info.height) from tb_course cross join
tb_students_info where tb_course.id = tb_studentss_info.course_id and tb_course.course_name = 'Java';
+-------------+------------------------------+
| course_name | avg(tb_students_info.height) |
+-------------+------------------------------+
| Java        |                        172.5 |
+-------------+------------------------------+
1 row in set (0.01 sec)

如果在交叉连接时使用 WHERE 子句，MySQL 会先生成两个表的笛卡尔积，然后再选择满足 WHERE 条件的记录。因此，表的数量较多时，交叉连接会非常非常慢。一般情况下不建议使用交叉连接。

在 MySQL 中，多表查询一般使用内连接和外连接，它们的效率要高于交叉连接。

3.3 内连接

内连接（INNER JOIN）主要通过设置连接条件的方式，来移除查询结果中某些数据行的交叉连接。简单来说，就是利用条件表达式来消除交叉连接的某些数据行。

内连接使用 INNER JOIN 关键字连接两张表，并使用 ON 子句来设置连接条件。如果没有连接条件，INNER JOIN 和 CROSS JOIN 在语法上是等同的，两者可以互换。

内连接的语法格式如下：

 SELECT <字段名> FROM <表1> INNER JOIN <表2> [ON子句];

INNER JOIN 也可以使用 WHERE 子句指定连接条件，但是 INNER JOIN ... ON 语法是官方的标准写法，而且 WHERE 子句在某些时候会影响查询的性能。

多个表内连接时，在 FROM 后连续使用 INNER JOIN 或 JOIN 即可。

内连接可以查询两个或两个以上的表。为了更好的理解，暂时只讲解两个表的连接查询。

 #在tb_students_info 表和 tb_course 表之间，使用内连接查询学生姓名和相对应的课程名称
mysql> select c.course_name,s.name  from tb_course c inner join tb_students_info s on c.id = s.course_id;	$(c 和 s分别是表tb_course和tb_students_iofo的别名)
+-------------+--------+
| course_name | name   |
+-------------+--------+
| Java        | Dany   |
| MySQL       | Green  |
| Java        | Henry  |
| Python      | Jane   |
| MySQL       | Jim    |
| Go          | John   |
| Go          | Lily   |
| C++         | Susan  |
| C++         | Thomas |
| C++         | Tom    |
+-------------+--------+
10 rows in set (0.00 sec)
 
#使用内连接查询学习Java的有哪些
mysql> select c.course_name,s.name  from tb_course c inner join tb_students_info s on c.id = s.course_id and c.course_name = 'Java';
+-------------+-------+
| course_name | name  |
+-------------+-------+
| Java        | Dany  |
| Java        | Henry |
+-------------+-------+
2 rows in set (0.00 sec)
 
#使用内连接查询学习Java和MySQL的有哪些人
mysql> select c.course_name,s.name  from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL');
+-------------+-------+
| course_name | name  |
+-------------+-------+
| Java        | Dany  |
| MySQL       | Green |
| Java        | Henry |
| MySQL       | Jim   |
+-------------+-------+
4 rows in set (0.00 sec)
 
#统计学习Java和MySQL的各多少人
mysql> select c.course_name,count(s.name)  from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
+-------------+---------------+
| course_name | count(s.name) |
+-------------+---------------+
| Java        |             2 |
| MySQL       |             2 |
+-------------+---------------+
2 rows in set (0.00 sec)
 
#查询学习Java和MySQL的有哪些人,使用group_concat()函数
mysql> select c.course_name,group_concat(s.name)  from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
+-------------+----------------------+
| course_name | group_concat(s.name) |
+-------------+----------------------+
| Java        | Henry,Dany           |
| MySQL       | Jim,Green            |
+-------------+----------------------+
2 rows in set (0.00 sec)
 
#查询学习Java和MySQL的有哪些人,并且显示平均年龄
mysql> select c.course_name,group_concat(s.name),avg(s.age)  from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.couurse_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
+-------------+----------------------+------------+
| course_name | group_concat(s.name) | avg(s.age) |
+-------------+----------------------+------------+
| Java        | Henry,Dany           |    24.0000 |
| MySQL       | Jim,Green            |    23.5000 |
+-------------+----------------------+------------+
2 rows in set (0.00 sec)

在这里的查询语句中，两个表之间的关系通过 INNER JOIN指定，连接的条件使用ON子句给出。

注意：当对多个表进行查询时，要在 SELECT 语句后面指定字段是来源于哪一张表。因此，在多表查询时，SELECT 语句后面的写法是表名.列名。另外，如果表名非常长的话，也可以给表设置别名，这样就可以直接在 SELECT 语句后面写上表的别名.列名。

3.4 外连接

内连接的查询结果都是符合连接条件的记录，而外连接会先将连接的表分为基表和参考表，再以基表为依据返回满足和不满足条件的记录。

外连接可以分为左外连接和右外连接2种，下面根据实例分别介绍左外连接和右外连接。

3.4.1 左连接

左外连接又称为左连接，使用 LEFT OUTER JOIN 关键字连接两个表，并使用 ON 子句来设置连接条件。

左连接的语法格式如下：

 SELECT <字段名> FROM <表1> LEFT OUTER JOIN <表2> <ON子句>;

上述语法中，"表1"为基表，"表2"为参考表。左连接查询时，可以查询出"表1"中的所有记录和"表2"中匹配连接条件的记录。如果"表1"的某行在"表2"中没有匹配行，那么在返回结果中，"表2"的字段值均为空值（NULL）

在进行左连接查询之前，我们先查看 tb_course 和 tb_students_info 两张表中的数据

 mysql> select * from tb_students_info;
+----+--------+------+--------+-----------+------+
| id | name   | age  | height | course_id | sex  |
+----+--------+------+--------+-----------+------+
|  1 | Dany   |   25 |    160 |         1 | M    |
|  2 | Green  |   23 |    158 |         2 | M    |
|  3 | Henry  |   23 |    185 |         1 | W    |
|  4 | Jane   |   22 |    162 |         3 | M    |
|  5 | Jim    |   24 |    175 |         2 | W    |
|  6 | John   |   21 |    172 |         4 | W    |
|  7 | Lily   |   22 |    165 |         4 | M    |
|  8 | Susan  |   23 |    170 |         5 | M    |
|  9 | Thomas |   22 |    178 |         5 | W    |
| 10 | Tom    |   23 |    165 |         5 | W    |
| 11 | LiMing |   22 |    180 |         7 | M    |
+----+--------+------+--------+-----------+------+
11 rows in set (0.00 sec)
 
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
+----+-------------+
6 rows in set (0.00 sec)

在 tb_students_info 表和 tb_course 表中查询所有学生姓名和相对应的课程名称，包括没有课程的学生

 mysql> select s.name,c.course_name from tb_students_info s left outer join tb_course c on s.course_id = c.id;
+--------+-------------+
| name   | course_name |
+--------+-------------+
| Dany   | Java        |
| Green  | MySQL       |
| Henry  | Java        |
| Jane   | Python      |
| Jim    | MySQL       |
| John   | Go          |
| Lily   | Go          |
| Susan  | C++         |
| Thomas | C++         |
| Tom    | C++         |
| LiMing | NULL        |
+--------+-------------+
11 rows in set (0.00 sec)

可以看到，运行结果显示了 11 条记录，name 为 LiMing 的学生目前没有课程，因为对应的 tb_course 表中没有该学生的课程信息，所以该条记录只取出了 tb_students_info 表中相应的值，而从 tb_course 表中取出的值为 NULL。

3.4.2 右连接

右外连接又称为右连接，右连接是左连接的反向连接。使用 RIGHT OUTER JOIN 关键字连接两个表，并使用 ON 子句来设置连接条件。

右连接的语法格式如下：

 SELECT <字段名> FROM <表1> RIGHT OUTER JOIN <表2> <ON子句>;

与左连接相反，右连接以"表2"为基表，"表1"为参考表。右连接查询时，可以查询出"表2"中的所有记录和"表1"中匹配连接条件的记录。如果"表2"的某行在"表1"中没有匹配行，那么在返回结果中，"表1"的字段值均为空值（NULL）

在 tb_students_info 表和 tb_course 表中查询所有课程，包括没有学生的课程，SQL 语句和运行结果如下:

 mysql> select s.name,c.course_name from tb_students_info s right outer join tb_course c on s.course_id = c.id;
+--------+-------------+
| name   | course_name |
+--------+-------------+
| Dany   | Java        |
| Green  | MySQL       |
| Henry  | Java        |
| Jane   | Python      |
| Jim    | MySQL       |
| John   | Go          |
| Lily   | Go          |
| Susan  | C++         |
| Thomas | C++         |
| Tom    | C++         |
| NULL   | HTML        |
+--------+-------------+
11 rows in set (0.00 sec)

可以看到，结果显示了 11 条记录，名称为 HTML 的课程目前没有学生，因为对应的tb_students_info 表中并没有该学生的信息，所以该条记录只取出了 tb_course 表中相应的值，而从 tb_students_info 表中取出的值为 NULL。

多个表左/右连接时，在 ON 子句后连续使用 LEFT/RIGHT OUTER JOIN 或 LEFT/RIGHT JOIN 即可。

使用外连接查询时，一定要分清需要查询的结果，是需要显示左表的全部记录还是右表的全部记录，然后选择相应的左连接和右连接。

3.5 分组查询

在 MySQL 中，GROUP BY 关键字可以根据一个或多个字段对查询结果进行分组。

使用 GROUP BY 关键字的语法格式如下：

 GROUP BY  <字段名>

其中，"字段名"表示需要分组的字段名称，多个字段时用逗号隔开。

3.5.1 group by 单独使用

单独使用 GROUP BY 关键字时，查询结果会只显示每个分组的第一条记录。

下面根据 tb_students_info 表中的 sex 字段进行分组查询：

 mysql> select * from tb_students_info group by sex;
+----+-------+------+--------+-----------+------+
| id | name  | age  | height | course_id | sex  |
+----+-------+------+--------+-----------+------+
|  1 | Dany  |   25 |    160 |         1 | M    |
|  3 | Henry |   23 |    185 |         1 | W    |
+----+-------+------+--------+-----------+------+

gourp by单独使用时，每个分组只显示一行数据

3.5.2 group by 与 group_concat()

GROUP BY 关键字可以和 GROUP_CONCAT() 函数一起使用。GROUP_CONCAT() 函数会把每个分组的字段值都显示出来。

下面根据 tb_students_info 表中的 sex 字段进行分组查询，使用 GROUP_CONCAT() 函数将每个分组的 name 字段的值都显示出来。

 mysql> select group_concat(name),sex from tb_students_info group by sex;
+-----------------------------------+------+
| group_concat(name)                | sex  |
+-----------------------------------+------+
| Dany,Green,Jane,Lily,Susan,LiMing | M    |
| Henry,Jim,John,Thomas,Tom         | W    |
+-----------------------------------+------+
2 rows in set (0.00 sec)

由结果可以看到，查询结果分为两组，sex 字段值为'M'的是一组，值为'W'的是一组，且每组的学生姓名都显示出来了。

根据 tb_students_info 表中的 sex 和 age 字段进行分组查询

 mysql> select group_concat(name),sex,age from tb_students_info group by sex,age;
+--------------------+------+------+
| group_concat(name) | sex  | age  |
+--------------------+------+------+
| Jane,Lily,LiMing   | M    |   22 |
| Green,Susan        | M    |   23 |
| Dany               | M    |   25 |
| John               | W    |   21 |
| Thomas             | W    |   22 |
| Henry,Tom          | W    |   23 |
| Jim                | W    |   24 |
+--------------------+------+------+
7 rows in set (0.00 sec)

上面实例在分组过程中，先按照 sex字段进行分组，当 age 字段值相等时，再把 sex 字段值相等的记录按照 age 字段进行分组。

多个字段分组查询时，会先按照第一个字段进行分组。如果第一个字段中有相同的值，MySQL 才会按照第二个字段进行分组。如果第一个字段中的数据都是唯一的，那么 MySQL 将不再对第二个字段进行分组。

3.5.3 group by 与函数聚合

GROUP BY 关键字经常和聚合函数一起使用

聚合函数包括 COUNT()，SUM()，AVG()，MAX() 和 MIN()。其中，COUNT() 用来统计记录的条数；SUM() 用来计算字段值的总和；AVG() 用来计算字段值的平均值；MAX() 用来查询字段的最大值；MIN() 用来查询字段的最小值。

根据 tb_students_info 表的 sex 字段进行分组查询，使用 COUNT() 函数计算每一组的记录数。

 mysql> select count(name),sex from tb_students_info group by sex;
+-------------+------+
| count(name) | sex  |
+-------------+------+
|           6 | M    |
|           5 | W    |
+-------------+------+
2 rows in set (0.00 sec)

结果显示男生有6人，女生有5人

3.5.4 group by 与 with rollup

WITH ROLLUP 关键字用来在所有记录的最后加上一条记录，这条记录是上面所有记录的总和，即统计记录数量。

根据 tb_students_info 表中的 sex 字段进行分组查询，并使用 WITH ROLLUP 显示记录的总和

 mysql> select group_concat(name),sex from tb_students_info group by sex with rollup;
+-------------------------------------------------------------+------+
| group_concat(name)                                          | sex  |
+-------------------------------------------------------------+------+
| Dany,Green,Jane,Lily,Susan,LiMing                           | M    |
| Henry,Jim,John,Thomas,Tom                                   | W    |
| Dany,Green,Jane,Lily,Susan,LiMing,Henry,Jim,John,Thomas,Tom | NULL |
+-------------------------------------------------------------+------+
3 rows in set (0.00 sec)

3.6 子查询

子查询是 MySQL 中比较常用的查询方法，通过子查询可以实现多表查询。子查询指将一个查询语句嵌套在另一个查询语句中。子查询可以在 SELECT、UPDATE 和 DELETE 语句中使用，而且可以进行多层嵌套。在实际开发时，子查询经常出现在 WHERE 子句中

子查询在 WHERE 中的语法格式如下：

 WHERE <表达式> <操作符> (子查询)

3.6.1 in | not in

当表达式与子查询返回的结果集中的某个值相等时，返回 TRUE，否则返回 FALSE；若使用关键字 NOT，则返回值正好相反。

使用子查询在 tb_students_info 表和 tb_course 表中查询学习 Java 课程的学生姓名

 mysql> select name from tb_students_info where course_id in (select id from tb_course where course_name = 'Java');
+-------+
| name  |
+-------+
| Dany  |
| Henry |
+-------+
2 rows in set (0.00 sec)

在 SELECT 语句中使用 NOT IN 关键字，查询没有学习 Java 课程的学生姓名

 mysql> select name from tb_students_info where  course_id not in (select id from tb_course where course_name = 'Java');		$(not in 可以使用"<>"代替)
+--------+
| name   |
+--------+
| Green  |
| Jane   |
| Jim    |
| John   |
| Lily   |
| Susan  |
| Thomas |
| Tom    |
| LiMing |
+--------+
9 rows in set (0.00 sec)

习惯上，外层的 SELECT 查询称为父查询，圆括号中嵌入的查询称为子查询（子查询必须放在括号内）。MySQL 在处理上例的 SELECT 语句时，执行流程为：先执行子查询，再执行父查询。

3.6.2 exists | not exists

用于判断子查询的结果集是否为空，若子查询的结果集不为空，返回 TRUE，否则返回 FALSE；若使用关键字 NOT，则返回的值正好相反。

查询 tb_course 表中是否存在 id=1 的课程，如果存在，就查询出 tb_students_info 表中的记录

 mysql> select * from tb_students_info where exists (select course_name from tb_course where id = 1);
+----+--------+------+--------+-----------+------+
| id | name   | age  | height | course_id | sex  |
+----+--------+------+--------+-----------+------+
|  1 | Dany   |   25 |    160 |         1 | M    |
|  2 | Green  |   23 |    158 |         2 | M    |
|  3 | Henry  |   23 |    185 |         1 | W    |
|  4 | Jane   |   22 |    162 |         3 | M    |
|  5 | Jim    |   24 |    175 |         2 | W    |
|  6 | John   |   21 |    172 |         4 | W    |
|  7 | Lily   |   22 |    165 |         4 | M    |
|  8 | Susan  |   23 |    170 |         5 | M    |
|  9 | Thomas |   22 |    178 |         5 | W    |
| 10 | Tom    |   23 |    165 |         5 | W    |
| 11 | LiMing |   22 |    180 |         7 | M    |
+----+--------+------+--------+-----------+------+
11 rows in set (0.00 sec)

由结果可以看到，tb_course 表中存在 id=1 的记录，因此 EXISTS 表达式返回 TRUE，外层查询语句接收 TRUE 之后对表 tb_students_info 进行查询，返回所有的记录。

EXISTS 关键字可以和其它查询条件一起使用，条件表达式与 EXISTS 关键字之间用 AND 和 OR 连接。

 #查询tb_course表中是否存在课程id为1的课程，如果有救查询tb_students_info表中age=22的记录
mysql> select * from tb_students_info where age = 22 and exists (select course_name from tb_course where id = 1);
+----+--------+------+--------+-----------+------+
| id | name   | age  | height | course_id | sex  |
+----+--------+------+--------+-----------+------+
|  4 | Jane   |   22 |    162 |         3 | M    |
|  7 | Lily   |   22 |    165 |         4 | M    |
|  9 | Thomas |   22 |    178 |         5 | W    |
| 11 | LiMing |   22 |    180 |         7 | M    |
+----+--------+------+--------+-----------+------+
4 rows in set (0.00 sec)

子查询比较灵活、方便、形式多样，适合作为查询的筛选条件，而表连接更适合于查看连接表的数据。

4.mysql数据库备份与恢复

4.1 数据库常用备份方案

全量备份
增量备份
差异备份

备份方案	特点
全量备份	全量备份就是指对某一个时间点上的所有数据或应用进行的一个完全拷贝。数据恢复快。备份时间长
增量备份	增量备份是指在一次全备份或上一次增量备份后，以后每次的备份只需备份与前一次相比增加和者被修改的文件。这就意味着，第一次增量备份的对象是进行全备后所产生的增加和修改的文件；第二次增量备份的对象是进行第一次增量备份后所产生的增加和修改的文件，如此类推。没有重复的备份数据备份时间短恢复数据时必须按一定的顺序进行
差异备份	备份上一次的完全备份后发生变化的所有文件。差异备份是指在一次全备份后到进行差异备份的这段时间内对那些增加或者修改文件的备份。在进行恢复时，我们只需对第一次全量备份和最后一次差异备份进行恢复。

4.2 mysql备份工具mysqldump

语法：

 mysqldump [OPTIONS] database [tables ...]
mysqldump [OPTIONS] --all-databases [OPTIONS]
mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...]

常用的OPTIONS：

 -uUSERNAME      指定数据库用户名
-hHOST          指定服务器主机，请使用ip地址
-pPASSWORD      指定数据库用户的密码
-P#             指定数据库监听的端口，这里的#需用实际的端口号代替，如-P3307

备份整个数据库(全备)

 mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zzd                |
+--------------------+
5 rows in set (0.00 sec)
 
mysql> use zzd;
Database changed
mysql> show tables;
+------------------+
| Tables_in_zzd    |
+------------------+
| tb_course        |
| tb_students_info |
+------------------+
2 rows in set (0.01 sec)
 
 
[root@zzd139 ~]# ls
anaconda-ks.cfg  pass
[root@zzd139 ~]# mysqldump --all-databases > all-`date +%Y-%m-%d:%H:%M:%S`.sql
[root@zzd139 ~]# ls
all-2022-07-28:21:26:56.sql  anaconda-ks.cfg  pass
$(这里mysqldump命令需要带上用户和密码，mysqldump -uroot -pxxxxx。因为麻烦和安全性考虑，可以编写文件.my.cnf文件针对与mysqldump命令不需要每次都输入密码和用户)
[root@zzd139 ~]# vim ~/.my.cnf 
	[mysqldump]
    user=root
    host=localhost
    password=xxxxx
$(下列4行是为了登录mysql不需要输入密码和用户的配置)
    [client]
    user=root
    host=localhost
    password=xxxxx
[root@zzd139 ~]# systemctl restart mysqld.service

备份zzd库的tb_students_info表和tb_course表

 [root@zzd139 ~]# mysqldump zzd tb_students_info tb_course > db_zzd-tables-`date +%Y-%m-%d:%H:%M:%S`.sql
[root@zzd139 ~]# ls
all-2022-07-28:21:26:56.sql  anaconda-ks.cfg  db_zzd-tables-2022-07-28:21:41:04.sql  pass

备份数据库zzd

 [root@zzd139 ~]# mysqldump --databases zzd > db_zzd-`date +%Y-%m-%d:%H:%M:%S`.sql
[root@zzd139 ~]# ls
all-2022-07-28:21:26:56.sql  anaconda-ks.cfg  db_zzd-2022-07-28:21:42:06.sql  db_zzd-tables-2022-07-28:21:41:04.sql  pass

4.3 mysql数据库恢复

 #模拟误删数据库zzd
mysql> drop database zzd;
Query OK, 2 rows affected (0.01 sec)
 
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)
 
#恢复数据库zzd
[root@zzd139 ~]# mysql < db_zzd-2022-07-28:21:42:06.sql 
 
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zzd                |
+--------------------+
5 rows in set (0.00 sec)
 
#恢复zzd数据库的tb_students_info表和tb_course表
mysql> use zzd;
Database changed
 
mysql> source db_zzd-tables-2022-07-28:21:41:04.sql
Query OK, 0 rows affected (0.00 sec)
………
Query OK, 0 rows affected (0.00 sec)
 
mysql> show tables;
+------------------+
| Tables_in_zzd    |
+------------------+
| tb_course        |
| tb_students_info |
+------------------+
2 rows in set (0.00 sec)
 
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
+----+-------------+
6 rows in set (0.00 sec)

4.4 差异备份与恢复

4.4.1 mysql差异备份

开启MySQL服务器的二进制日志功能

 [root@zzd139 ~]# vim /etc/my.cnf 
    server-id = 1
    log-bin = mysql_bin
[root@zzd139 ~]# systemctl restart mysqld.service

对数据库进行完全备份

 [root@zzd139 ~]# mysqldump --single-transaction --flush-logs --master-data=2 --all-databases --delete-master-logs > all-`date +%Y-%m-%d:%H:%M:%S`.sql
[root@zzd139 ~]# ls all-2022-07-28\:22\:10\:32.sql 
all-2022-07-28:22:10:32.sql
 
#增加新内容
[root@zzd139 ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.38-log MySQL Community Server (GPL)
 
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
 
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>use zzd;
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> insert into tb_course(course_name) values('C#'),('PHP');
Query OK, 2 rows affected (0.01 sec)
Records: 2  Duplicates: 0  Warnings: 0
 
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
|  7 | C#          |
|  8 | PHP         |
+----+-------------+
8 rows in set (0.00 sec)

4.2.2 mysql差异备份恢复

模拟误删数据

 mysql> drop database zzd;
Query OK, 2 rows affected (0.00 sec)
 
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

刷新创建的二进制日志

 [root@zzd139 ~]# ll /opt/mysql/data/
total 123052
-rw-r-----. 1 mysql mysql       56 Jul 27 17:09 auto.cnf
-rw-------. 1 mysql mysql     1680 Jul 27 17:09 ca-key.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 ca.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 client-cert.pem
-rw-------. 1 mysql mysql     1676 Jul 27 17:09 client-key.pem
-rw-r-----. 1 mysql mysql      390 Jul 28 22:05 ib_buffer_pool
-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:20 ibdata1
-rw-r-----. 1 mysql mysql 50331648 Jul 28 22:20 ib_logfile0
-rw-r-----. 1 mysql mysql 50331648 Jul 27 17:09 ib_logfile1
-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:10 ibtmp1
drwxr-x---. 2 mysql mysql     4096 Jul 27 17:09 mysql
-rw-r-----. 1 mysql mysql      581 Jul 28 22:20 mysql_bin.000002
-rw-r-----. 1 mysql mysql       19 Jul 28 22:10 mysql_bin.index
-rw-r-----. 1 mysql mysql        5 Jul 28 22:05 mysql.pid
drwxr-x---. 2 mysql mysql     8192 Jul 27 17:09 performance_schema
-rw-------. 1 mysql mysql     1680 Jul 27 17:09 private_key.pem
-rw-r--r--. 1 mysql mysql      452 Jul 27 17:09 public_key.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 server-cert.pem
-rw-------. 1 mysql mysql     1676 Jul 27 17:09 server-key.pem
drwxr-x---. 2 mysql mysql     8192 Jul 27 17:09 sys
-rw-r-----. 1 mysql mysql    92152 Jul 28 22:05 zzd139.err
#刷新创建新的二进制日志
[root@zzd139 ~]# mysqladmin -uroot -p flush-logs 
Enter password: 
[root@zzd139 ~]# ll /opt/mysql/data/
total 123056
-rw-r-----. 1 mysql mysql       56 Jul 27 17:09 auto.cnf
-rw-------. 1 mysql mysql     1680 Jul 27 17:09 ca-key.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 ca.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 client-cert.pem
-rw-------. 1 mysql mysql     1676 Jul 27 17:09 client-key.pem
-rw-r-----. 1 mysql mysql      390 Jul 28 22:05 ib_buffer_pool
-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:23 ibdata1
-rw-r-----. 1 mysql mysql 50331648 Jul 28 22:23 ib_logfile0
-rw-r-----. 1 mysql mysql 50331648 Jul 27 17:09 ib_logfile1
-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:10 ibtmp1
drwxr-x---. 2 mysql mysql     4096 Jul 27 17:09 mysql
-rw-r-----. 1 mysql mysql      628 Jul 28 22:23 mysql_bin.000002
-rw-r-----. 1 mysql mysql      154 Jul 28 22:23 mysql_bin.000003
-rw-r-----. 1 mysql mysql       38 Jul 28 22:23 mysql_bin.index
-rw-r-----. 1 mysql mysql        5 Jul 28 22:05 mysql.pid
drwxr-x---. 2 mysql mysql     8192 Jul 27 17:09 performance_schema
-rw-------. 1 mysql mysql     1680 Jul 27 17:09 private_key.pem
-rw-r--r--. 1 mysql mysql      452 Jul 27 17:09 public_key.pem
-rw-r--r--. 1 mysql mysql     1112 Jul 27 17:09 server-cert.pem
-rw-------. 1 mysql mysql     1676 Jul 27 17:09 server-key.pem
drwxr-x---. 2 mysql mysql     8192 Jul 27 17:09 sys
-rw-r-----. 1 mysql mysql    92152 Jul 28 22:05 zzd139.err

恢复完全备份

 [root@zzd139 ~]# mysql < all-2022-07-28\:22\:10\:32.sql 
[root@zzd139 ~]# mysql -e 'show databases;'
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zzd                |
+--------------------+
 
[root@zzd139 ~]# mysql -e 'show tables from zzd;'
+------------------+
| Tables_in_zzd    |
+------------------+
| tb_course        |
| tb_students_info |
+------------------+
 
[root@zzd139 ~]# mysql -e 'select * from zzd.tb_course;'
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
+----+-------------+

恢复差异备份

 #检查误删数据库的位置在什么地方
mysql> show binlog events in 'mysql_bin.000002';
+------------------+-----+----------------+-----------+-------------+---------------------------------------+
| Log_name         | Pos | Event_type     | Server_id | End_log_pos | Info                                  |
+------------------+-----+----------------+-----------+-------------+---------------------------------------+
| mysql_bin.000002 |   4 | Format_desc    |         1 |         123 | Server ver: 5.7.38-log, Binlog ver: 4 |
| mysql_bin.000002 | 123 | Previous_gtids |         1 |         154 |                                       |
| mysql_bin.000002 | 154 | Anonymous_Gtid |         1 |         219 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'  |
| mysql_bin.000002 | 219 | Query          |         1 |         290 | BEGIN                                 |
| mysql_bin.000002 | 290 | Table_map      |         1 |         344 | table_id: 140 (zzd.tb_course)         |
| mysql_bin.000002 | 344 | Write_rows     |         1 |         396 | table_id: 140 flags: STMT_END_F       |
| mysql_bin.000002 | 396 | Xid            |         1 |         427 | COMMIT /* xid=481 */                  |
| mysql_bin.000002 | 427 | Anonymous_Gtid |         1 |         492 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'  |
| mysql_bin.000002 | 492 | Query          |         1 |         581 | drop database zzd                     |
| mysql_bin.000002 | 581 | Rotate         |         1 |         628 | mysql_bin.000003;pos=4                |
+------------------+-----+----------------+-----------+-------------+---------------------------------------+
10 rows in set (0.00 sec)
 
#使用mysqlbinlog恢复差异备份
[root@zzd139 ~]# mysqlbinlog  --stop-position=492 /opt/mysql/data/mysql_bin.000002 | mysql
[root@zzd139 ~]# mysql -e 'select * from zzd.tb_course;'
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
|  7 | C#          |
|  8 | PHP         |
+----+-------------+

4.2.3 使用二进制日志进行恢复备份

 #模拟误删数据库
mysql> drop database zzd;
Query OK, 2 rows affected (0.00 sec)
 
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)
 
#进行全量恢复
[root@zzd139 ~]# mysql < all-2022-07-28\:22\:10\:32.sql
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| zzd                |
+--------------------+
5 rows in set (0.00 sec)
 
mysql> use zzd;
 
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
+----+-------------+
6 rows in set (0.00 sec)
 
#将刷新日志
mysql> flush logs;
Query OK, 0 rows affected (0.00 sec)
 
#将二进制日志转换为可读的文本文件
[root@zzd139 ~]# mysqlbinlog --no-defaults --base64-output=decode-rows -v /opt/mysql/data/mysql_bin.000002 > /root/mysql_bin002.txt
 
[root@zzd139 ~]# file mysql_bin002.txt 
mysql_bin002.txt: ASCII text
 
#在文件mysql_bin002.txt中找到最后在tb_course表中插入数据的操作id，然后按照操作id进行恢复
[root@zzd139 ~]# mysqlbinlog --stop-position=427 /opt/mysql/data/mysql_bin.000002 | mysql
 
#验证结果
mysql> select * from tb_course;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | Java        |
|  2 | MySQL       |
|  3 | Python      |
|  4 | Go          |
|  5 | C++         |
|  6 | HTML        |
|  7 | C#          |
|  8 | PHP         |
+----+-------------+
8 rows in set (0.00 sec)
 
#按照时间恢复，只需要找到具体操作时间然后改变一下参数和时间格式就可以了
[root@zzd139 ~]# mysqlbinlog --stop-datetime='22-07-28 22:20:55' /opt/mysql/data/mysql_bin.000002 | mysql

posted @ 2022-08-01 20:38 Zic师傅阅读(125) 评论(0) 编辑收藏举报

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相关博文：

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· mysql进阶

阅读目录(Content)

mysql进阶

1.安装mysql

1.1 mysql二进制安装
1.2 mysql破解密码

2.mysql配置文件
3.多表联查

3.1 什么是多表联查
3.2 交叉连接(CROSS JOIN)
3.3 内连接
3.4 外连接
3.5 分组查询
3.6 子查询

4.mysql数据库备份与恢复

4.2 mysql备份工具mysqldump
4.3 mysql数据库恢复
4.4 差异备份与恢复

	#创建mysql用户
	[root@zzd139 ~]# useradd -Mrs /sbin/nologin mysql

	#安装ncurses-compat-libs
	[root@zzd139 ~]# dnf -y install ncurses-compat-libs

	#将mysql二进制包解压到/usr/local/目录下
	[root@zzd139 ~]# tar xf mysql-5.7.38-linux-glibc2.12-x86_64.tar.gz -C /usr/local/
	[root@zzd139 local]# ln -sv mysql-5.7.38-linux-glibc2.12-x86_64/ mysql
	'mysql' -> 'mysql-5.7.38-linux-glibc2.12-x86_64/'
	[root@zzd139 local]# ll
	total 0
	drwxr-xr-x. 2 root root 6 May 19 2020 bin
	drwxr-xr-x. 2 root root 6 May 19 2020 etc
	drwxr-xr-x. 2 root root 6 May 19 2020 games
	drwxr-xr-x. 2 root root 6 May 19 2020 include
	drwxr-xr-x. 2 root root 6 May 19 2020 lib
	drwxr-xr-x. 3 root root 17 Jun 28 09:25 lib64
	drwxr-xr-x. 2 root root 6 May 19 2020 libexec
	lrwxrwxrwx. 1 root root 36 Jul 27 16:54 mysql -> mysql-5.7.38-linux-glibc2.12-x86_64/
	drwxr-xr-x. 9 root root 129 Jul 27 16:53 mysql-5.7.38-linux-glibc2.12-x86_64
	drwxr-xr-x. 2 root root 6 May 19 2020 sbin
	drwxr-xr-x. 5 root root 49 Jun 28 09:25 share
	drwxr-xr-x. 2 root root 6 May 19 2020 src
	[root@zzd139 local]# cd mysql
	[root@zzd139 mysql]# ls
	bin docs include lib LICENSE man README share support-files

	#修改目录/usr/local/mysql的属主属组
	[root@zzd139 mysql]# chown -R mysql.mysql /usr/local/mysql
	[root@zzd139 mysql]# chown -R mysql.mysql /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/
	[root@zzd139 mysql]# ll -d /usr/local/mysql
	lrwxrwxrwx. 1 mysql mysql 36 Jul 27 16:54 /usr/local/mysql -> mysql-5.7.38-linux-glibc2.12-x86_64/
	[root@zzd139 mysql]# ll -d /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/
	drwxr-xr-x. 9 mysql mysql 129 Jul 27 16:53 /usr/local/mysql-5.7.38-linux-glibc2.12-x86_64/

	#配置mysql全局环境变量
	[root@zzd139 mysql]# echo "export PATH=$PATH:/usr/local/mysql/bin" > /etc/profile.d/mysql.sh
	[root@zzd139 mysql]# source /etc/profile.d/mysql.sh
	[root@zzd139 mysql]# echo $PATH
	/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin:/usr/local/mysql/bin

	#将mysql头文件添加至系统默认识别的目录/usr/include
	[root@zzd139 mysql]# ln -sv /usr/local/mysql/include/ /usr/include/mysql
	'/usr/include/mysql' -> '/usr/local/mysql/include/'
	[root@zzd139 mysql]# ll -d /usr/include/mysql
	lrwxrwxrwx. 1 root root 25 Jul 27 16:58 /usr/include/mysql -> /usr/local/mysql/include/

	#将mysql的lib库文件添加到系统识别文件
	[root@zzd139 mysql]# echo "/usr/local/mysql/lib/" > /etc/ld.so.conf.d/mysql.conf
	[root@zzd139 mysql]# ldconfig

	#添加man文档
	[root@zzd139 mysql]# vim /etc/man_db.conf
	$(添加如下内容)
	MANDATORY_MANPATH /usr/local/mysql/man

	#建立存放数据目录
	[root@zzd139 mysql]# mkdir -p /opt/mysql/data
	[root@zzd139 mysql]# chown -R mysql.mysql /opt/mysql/
	[root@zzd139 mysql]# ll /opt/mysql/
	total 0
	drwxr-xr-x. 2 mysql mysql 6 Jul 27 17:06 data

	#初始化数据库
	[root@zzd139 ~]# mysqld --initialize --user=mysql --datadir=/opt/mysql/data
	2022-07-27T09:09:13.223427Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
	2022-07-27T09:09:13.386290Z 0 [Warning] InnoDB: New log files created, LSN=45790
	2022-07-27T09:09:13.429221Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
	2022-07-27T09:09:13.485193Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: c8900af2-0d8b-11ed-b3bc-000c29f177ce.
	2022-07-27T09:09:13.485726Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
	2022-07-27T09:09:13.674856Z 0 [Warning] A deprecated TLS version TLSv1 is enabled. Please use TLSv1.2 or higher.
	2022-07-27T09:09:13.674870Z 0 [Warning] A deprecated TLS version TLSv1.1 is enabled. Please use TLSv1.2 or higher.
	2022-07-27T09:09:13.675192Z 0 [Warning] CA certificate ca.pem is self signed.
	2022-07-27T09:09:13.746758Z 1 [Note] A temporary password is generated for root@localhost: oGDSXemN0u=f
	#oGDSXemN0u=f就是mysql的密码，每次初始化密码都不一样，所以登录后首先修改密码，我们先将这个密码保存起来以防忘记
	[root@zzd139 ~]# echo oGDSXemN0u=f > pass
	[root@zzd139 ~]# cat pass
	oGDSXemN0u=f

	#生成配置文件
	[root@zzd139 ~]# vim /etc/my.cnf
	[mysqld]
	basedir = /usr/local/mysql
	datadir = /opt/mysql/data
	socket = /tmp/mysql.sock
	port = 3306
	pid-file = /opt/mysql/data/mysql.pid
	user = mysql
	skip-name-resolve
	sql-mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
	[root@zzd139 system]# chown -R mysql.mysql /etc/my.cnf

	#启动mysql
	[root@zzd139 ~]# /usr/local/mysql/support-files/mysql.server start
	Starting MySQL.Logging to '/opt/mysql/data/zzd139.err'.
	SUCCESS!
	#关闭mysql
	[root@zzd139 ~]# /usr/local/mysql/support-files/mysql.server stop
	Shutting down MySQL.. SUCCESS!

	#使用systemd风格管理mysql服务
	[root@zzd139 ~]# cd /usr/lib/systemd/system
	[root@zzd139 system]# cp sshd.service mysqld.service
	[root@zzd139 system]# vim mysqld.service
	[Unit]
	Description=mysql server daemon
	After=network.target sshd-keygen.target

	[Service]
	Type=forking
	ExecStart=/usr/local/mysql/support-files/mysql.server start
	ExecStop=/usr/local/mysql/support-files/mysql.server stop
	ExecReload=/bin/kill -HUP $MAINPID

	[Install]
	WantedBy=multi-user.target
	[root@zzd139 system]# systemctl daemon-reload
	[root@zzd139 system]# setenforce 0
	$(这里还需要设置防火墙规则允许3306端口通过，觉得麻烦的话可以直接关闭防火墙)
	[root@zzd139 system]# systemctl start mysqld.service
	[root@zzd139 system]# systemctl status mysqld.service
	● mysqld.service - mysql server daemon
	Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
	Active: active (running) since Wed 2022-07-27 17:29:52 CST; 2min 1s ago
	Process: 3261 ExecStart=/usr/local/mysql/support-files/mysql.server start (code=exited, status=0/SUCCESS)
	Main PID: 3274 (mysqld_safe)
	Tasks: 28 (limit: 5770)
	Memory: 173.4M
	CGroup: /system.slice/mysqld.service
	├─3274 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/opt/mysql/data --pid-file=/opt/mysql/data/mysql.pid
	└─3476 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/opt/mysql/data --plugin-dir=/usr/local/mysql/lib/plugi>

	Jul 27 17:29:51 zzd139 systemd[1]: Starting mysql server daemon...
	Jul 27 17:29:52 zzd139 mysql.server[3261]: Starting MySQL. SUCCESS!
	Jul 27 17:29:52 zzd139 systemd[1]: Started mysql server daemon.
	[root@zzd139 system]# ss -antl
	State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
	LISTEN 0 128 0.0.0.0:111 0.0.0.0:*
	LISTEN 0 128 0.0.0.0:22 0.0.0.0:*
	LISTEN 0 80 :3306 :*
	LISTEN 0 128 [::]:111 [::]:*
	LISTEN 0 128 [::]:22 [::]:*

	#登录mysql修改密码
	$(使用初始化时的临时密码)
	[root@zzd139 ~]# mysql -uroot -poGDSXemN0u=f
	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 3
	Server version: 5.7.38

	Copyright (c) 2000, 2022, Oracle and/or its affiliates.

	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.

	#使用下列sql语句修改密码
	mysql> set password = password('xxxx'); $(括号里为密码)
	Query OK, 0 rows affected, 1 warning (0.00 sec)

	[root@zzd139 ~]# dnf provides libncurses.so.5
	Last metadata expiration check: 8:00:13 ago on Wed 27 Jul 2022 09:35:30 AM CST.
	ncurses-compat-libs-6.1-9.20180224.el8.i686 : Ncurses compatibility libraries
	Repo : BaseOS
	Matched from:
	Provide : libncurses.so.5

	#安装ncurses-compat-libs包即可
	[root@zzd139 ~]# dnf -y install ncurses-compat-libs

	#修改mysql配置文件
	[root@zzd139 ~]# vim /etc/my.cnf
	$(添加如下内容)
	skip-grant-tables
	#重启mysql服务
	[root@zzd139 ~]# systemctl restart mysqld.service
	#登录mysql
	[root@zzd139 ~]# mysql
	Welcome to the MySQL monitor. Commands end with ; or \g.
	Your MySQL connection id is 2
	Server version: 5.7.38 MySQL Community Server (GPL)

	Copyright (c) 2000, 2022, Oracle and/or its affiliates.

	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>

	#修改mysql的root用户密码
	mysql> update mysql.user set authentication_string = password('xxxxxx') where User = 'root' and Host = 'localhost';
	Query OK, 1 row affected, 1 warning (0.00 sec)
	Rows matched: 1 Changed: 1 Warnings: 1

	#再次修改my.cnf文件
	$(删除或注释如下内容)
	skip-grant-tables
	#重启mysql
	[root@zzd139 ~]# systemctl restart mysqld.service

	A×B={(1,3), (1,4), (1,5), (2,3), (2,4), (2,5) };
	B×A={(3,1), (3,2), (4,1), (4,2), (5,1), (5,2) };

	#创建数据库zzd
	mysql> create database zzd;
	Query OK, 1 row affected (0.01 sec)

	#创建tb_students_info表
	mysql> use zzd;
	Database changed
	mysql> create table tb_students_info(id int not null primary key auto_increment,name varchar(50),age tinyint,height float,course_id int);
	Query OK, 0 rows affected (0.00 sec)

	mysql> desc tb_students_info;
	+-----------+-------------+------+-----+---------+----------------+
	\| Field \| Type \| Null \| Key \| Default \| Extra \|
	+-----------+-------------+------+-----+---------+----------------+
	\| id \| int(11) \| NO \| PRI \| NULL \| auto_increment \|
	\| name \| varchar(50) \| YES \| \| NULL \| \|
	\| age \| tinyint(4) \| YES \| \| NULL \| \|
	\| height \| float \| YES \| \| NULL \| \|
	\| course_id \| int(11) \| YES \| \| NULL \| \|
	+-----------+-------------+------+-----+---------+----------------+
	5 rows in set (0.02 sec)

	#插入数据
	mysql> insert into tb_students_info(name,age,height,course_id) values('Dany',25,160,1),('Green',23,158,2),('Henry',23,185,1),('Jane',22,162,,3),('Jim',24,175,2),('John',21,172,4),('Lily',22,165,4),('Susan',23,170,5),('Thomas',22,178,5),('Tom',23,165,5);
	Query OK, 10 rows affected (0.00 sec)
	Records: 10 Duplicates: 0 Warnings: 0

	#查询表tb_students_info的记录
	mysql> select * from tb_students_info;
	+----+--------+------+--------+-----------+
	\| id \| name \| age \| height \| course_id \|
	+----+--------+------+--------+-----------+
	\| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 6 \| John \| 21 \| 172 \| 4 \|
	\| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 10 \| Tom \| 23 \| 165 \| 5 \|
	+----+--------+------+--------+-----------+
	10 rows in set (0.00 sec)

	#创建tb_course表
	mysql> create table tb_course(id int not null primary key auto_increment,course_name varchar(50));
	Query OK, 0 rows affected (0.00 sec)

	mysql> desc tb_course;
	+-------------+-------------+------+-----+---------+----------------+
	\| Field \| Type \| Null \| Key \| Default \| Extra \|
	+-------------+-------------+------+-----+---------+----------------+
	\| id \| int(11) \| NO \| PRI \| NULL \| auto_increment \|
	\| course_name \| varchar(50) \| YES \| \| NULL \| \|
	+-------------+-------------+------+-----+---------+----------------+
	2 rows in set (0.00 sec)

	#插入数据
	mysql> insert into tb_course(course_name) values('Java'),('MySQL'),('Python'),('Go'),('C++');
	Query OK, 5 rows affected (0.00 sec)
	Records: 5 Duplicates: 0 Warnings: 0

	mysql> select * from tb_course;
	+----+-------------+
	\| id \| course_name \|
	+----+-------------+
	\| 1 \| Java \|
	\| 2 \| MySQL \|
	\| 3 \| Python \|
	\| 4 \| Go \|
	\| 5 \| C++ \|
	+----+-------------+
	5 rows in set (0.00 sec)

	mysql> select * from tb_course cross join tb_students_info;
	+----+-------------+----+--------+------+--------+-----------+
	\| id \| course_name \| id \| name \| age \| height \| course_id \|
	+----+-------------+----+--------+------+--------+-----------+
	\| 1 \| Java \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 2 \| MySQL \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 3 \| Python \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 4 \| Go \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 5 \| C++ \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 1 \| Java \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 2 \| MySQL \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 3 \| Python \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 4 \| Go \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 5 \| C++ \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 1 \| Java \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 2 \| MySQL \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 3 \| Python \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 4 \| Go \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 5 \| C++ \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 1 \| Java \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 2 \| MySQL \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 3 \| Python \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 4 \| Go \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 5 \| C++ \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 1 \| Java \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 2 \| MySQL \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 3 \| Python \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 4 \| Go \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 5 \| C++ \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 1 \| Java \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 2 \| MySQL \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 3 \| Python \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 4 \| Go \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 5 \| C++ \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 1 \| Java \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 2 \| MySQL \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 3 \| Python \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 4 \| Go \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 5 \| C++ \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 1 \| Java \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 2 \| MySQL \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 3 \| Python \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 4 \| Go \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 5 \| C++ \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 1 \| Java \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 2 \| MySQL \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 3 \| Python \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 4 \| Go \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 5 \| C++ \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 1 \| Java \| 10 \| Tom \| 23 \| 165 \| 5 \|
	\| 2 \| MySQL \| 10 \| Tom \| 23 \| 165 \| 5 \|
	\| 3 \| Python \| 10 \| Tom \| 23 \| 165 \| 5 \|
	\| 4 \| Go \| 10 \| Tom \| 23 \| 165 \| 5 \|
	\| 5 \| C++ \| 10 \| Tom \| 23 \| 165 \| 5 \|
	+----+-------------+----+--------+------+--------+-----------+
	50 rows in set (0.00 sec)

	#查询 tb_course 表中的 id 字段和 tb_students_info 表中的 course_id 字段相等的内容
	mysql> select * from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id;
	+----+-------------+----+--------+------+--------+-----------+
	\| id \| course_name \| id \| name \| age \| height \| course_id \|
	+----+-------------+----+--------+------+--------+-----------+
	\| 1 \| Java \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| 2 \| MySQL \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| 1 \| Java \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| 3 \| Python \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| 2 \| MySQL \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| 4 \| Go \| 6 \| John \| 21 \| 172 \| 4 \|
	\| 4 \| Go \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| 5 \| C++ \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| 5 \| C++ \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| 5 \| C++ \| 10 \| Tom \| 23 \| 165 \| 5 \|
	+----+-------------+----+--------+------+--------+-----------+
	10 rows in set (0.00 sec)

	#查询 tb_course 表中的 id 字段和 tb_students_info 表中的 course_id 字段相等的内容,不显示tb_course表的id字段
	mysql> select tb_course.course_name,tb_students_info.* from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id;
	+-------------+----+--------+------+--------+-----------+
	\| course_name \| id \| name \| age \| height \| course_id \|
	+-------------+----+--------+------+--------+-----------+
	\| Java \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| MySQL \| 2 \| Green \| 23 \| 158 \| 2 \|
	\| Java \| 3 \| Henry \| 23 \| 185 \| 1 \|
	\| Python \| 4 \| Jane \| 22 \| 162 \| 3 \|
	\| MySQL \| 5 \| Jim \| 24 \| 175 \| 2 \|
	\| Go \| 6 \| John \| 21 \| 172 \| 4 \|
	\| Go \| 7 \| Lily \| 22 \| 165 \| 4 \|
	\| C++ \| 8 \| Susan \| 23 \| 170 \| 5 \|
	\| C++ \| 9 \| Thomas \| 22 \| 178 \| 5 \|
	\| C++ \| 10 \| Tom \| 23 \| 165 \| 5 \|
	+-------------+----+--------+------+--------+-----------+
	10 rows in set (0.00 sec)

	#把两个表交叉查询，只查询学习java的学生信息
	mysql> select tb_course.course_name,tb_students_info.* from tb_course cross join tb_students_info where tb_course.id = tb_students_info.course_id and tb_course.course_name = 'Java';
	+-------------+----+-------+------+--------+-----------+
	\| course_name \| id \| name \| age \| height \| course_id \|
	+-------------+----+-------+------+--------+-----------+
	\| Java \| 1 \| Dany \| 25 \| 160 \| 1 \|
	\| Java \| 3 \| Henry \| 23 \| 185 \| 1 \|
	+-------------+----+-------+------+--------+-----------+
	2 rows in set (0.00 sec)

	#查看学习java的学生的身高
	mysql> select tb_course.course_name,tb_students_info.height from tb_course cross join tb_students_info where tb_course.id = tb_students_infoo.course_id and tb_course.course_name = 'Java';
	+-------------+--------+
	\| course_name \| height \|
	+-------------+--------+
	\| Java \| 160 \|
	\| Java \| 185 \|
	+-------------+--------+
	2 rows in set (0.00 sec)

	#查看学习java的学生的平均升高
	mysql> select tb_course.course_name,avg(tb_students_info.height) from tb_course cross join
	tb_students_info where tb_course.id = tb_studentss_info.course_id and tb_course.course_name = 'Java';
	+-------------+------------------------------+
	\| course_name \| avg(tb_students_info.height) \|
	+-------------+------------------------------+
	\| Java \| 172.5 \|
	+-------------+------------------------------+
	1 row in set (0.01 sec)

	#在tb_students_info 表和 tb_course 表之间，使用内连接查询学生姓名和相对应的课程名称
	mysql> select c.course_name,s.name from tb_course c inner join tb_students_info s on c.id = s.course_id; $(c 和 s分别是表tb_course和tb_students_iofo的别名)
	+-------------+--------+
	\| course_name \| name \|
	+-------------+--------+
	\| Java \| Dany \|
	\| MySQL \| Green \|
	\| Java \| Henry \|
	\| Python \| Jane \|
	\| MySQL \| Jim \|
	\| Go \| John \|
	\| Go \| Lily \|
	\| C++ \| Susan \|
	\| C++ \| Thomas \|
	\| C++ \| Tom \|
	+-------------+--------+
	10 rows in set (0.00 sec)

	#使用内连接查询学习Java的有哪些
	mysql> select c.course_name,s.name from tb_course c inner join tb_students_info s on c.id = s.course_id and c.course_name = 'Java';
	+-------------+-------+
	\| course_name \| name \|
	+-------------+-------+
	\| Java \| Dany \|
	\| Java \| Henry \|
	+-------------+-------+
	2 rows in set (0.00 sec)

	#使用内连接查询学习Java和MySQL的有哪些人
	mysql> select c.course_name,s.name from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL');
	+-------------+-------+
	\| course_name \| name \|
	+-------------+-------+
	\| Java \| Dany \|
	\| MySQL \| Green \|
	\| Java \| Henry \|
	\| MySQL \| Jim \|
	+-------------+-------+
	4 rows in set (0.00 sec)

	#统计学习Java和MySQL的各多少人
	mysql> select c.course_name,count(s.name) from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
	+-------------+---------------+
	\| course_name \| count(s.name) \|
	+-------------+---------------+
	\| Java \| 2 \|
	\| MySQL \| 2 \|
	+-------------+---------------+
	2 rows in set (0.00 sec)

	#查询学习Java和MySQL的有哪些人,使用group_concat()函数
	mysql> select c.course_name,group_concat(s.name) from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.course_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
	+-------------+----------------------+
	\| course_name \| group_concat(s.name) \|
	+-------------+----------------------+
	\| Java \| Henry,Dany \|
	\| MySQL \| Jim,Green \|
	+-------------+----------------------+
	2 rows in set (0.00 sec)

	#查询学习Java和MySQL的有哪些人,并且显示平均年龄
	mysql> select c.course_name,group_concat(s.name),avg(s.age) from tb_course c inner join tb_students_info s on c.id = s.course_id and (c.couurse_name = 'Java' or c.course_name = 'MySQL') group by c.course_name;
	+-------------+----------------------+------------+
	\| course_name \| group_concat(s.name) \| avg(s.age) \|
	+-------------+----------------------+------------+
	\| Java \| Henry,Dany \| 24.0000 \|
	\| MySQL \| Jim,Green \| 23.5000 \|
	+-------------+----------------------+------------+
	2 rows in set (0.00 sec)

	mysql> select s.name,c.course_name from tb_students_info s left outer join tb_course c on s.course_id = c.id;
	+--------+-------------+
	\| name \| course_name \|
	+--------+-------------+
	\| Dany \| Java \|
	\| Green \| MySQL \|
	\| Henry \| Java \|
	\| Jane \| Python \|
	\| Jim \| MySQL \|
	\| John \| Go \|
	\| Lily \| Go \|
	\| Susan \| C++ \|
	\| Thomas \| C++ \|
	\| Tom \| C++ \|
	\| LiMing \| NULL \|
	+--------+-------------+
	11 rows in set (0.00 sec)

	mysql> select * from tb_students_info group by sex;
	+----+-------+------+--------+-----------+------+
	\| id \| name \| age \| height \| course_id \| sex \|
	+----+-------+------+--------+-----------+------+
	\| 1 \| Dany \| 25 \| 160 \| 1 \| M \|
	\| 3 \| Henry \| 23 \| 185 \| 1 \| W \|
	+----+-------+------+--------+-----------+------+

	mysql> select group_concat(name),sex from tb_students_info group by sex;
	+-----------------------------------+------+
	\| group_concat(name) \| sex \|
	+-----------------------------------+------+
	\| Dany,Green,Jane,Lily,Susan,LiMing \| M \|
	\| Henry,Jim,John,Thomas,Tom \| W \|
	+-----------------------------------+------+
	2 rows in set (0.00 sec)

	mysql> select group_concat(name),sex,age from tb_students_info group by sex,age;
	+--------------------+------+------+
	\| group_concat(name) \| sex \| age \|
	+--------------------+------+------+
	\| Jane,Lily,LiMing \| M \| 22 \|
	\| Green,Susan \| M \| 23 \|
	\| Dany \| M \| 25 \|
	\| John \| W \| 21 \|
	\| Thomas \| W \| 22 \|
	\| Henry,Tom \| W \| 23 \|
	\| Jim \| W \| 24 \|
	+--------------------+------+------+
	7 rows in set (0.00 sec)

	mysql> select count(name),sex from tb_students_info group by sex;
	+-------------+------+
	\| count(name) \| sex \|
	+-------------+------+
	\| 6 \| M \|
	\| 5 \| W \|
	+-------------+------+
	2 rows in set (0.00 sec)

	mysql> select group_concat(name),sex from tb_students_info group by sex with rollup;
	+-------------------------------------------------------------+------+
	\| group_concat(name) \| sex \|
	+-------------------------------------------------------------+------+
	\| Dany,Green,Jane,Lily,Susan,LiMing \| M \|
	\| Henry,Jim,John,Thomas,Tom \| W \|
	\| Dany,Green,Jane,Lily,Susan,LiMing,Henry,Jim,John,Thomas,Tom \| NULL \|
	+-------------------------------------------------------------+------+
	3 rows in set (0.00 sec)

	mysql> select name from tb_students_info where course_id in (select id from tb_course where course_name = 'Java');
	+-------+
	\| name \|
	+-------+
	\| Dany \|
	\| Henry \|
	+-------+
	2 rows in set (0.00 sec)

	mysql> select name from tb_students_info where course_id not in (select id from tb_course where course_name = 'Java'); $(not in 可以使用"<>"代替)
	+--------+
	\| name \|
	+--------+
	\| Green \|
	\| Jane \|
	\| Jim \|
	\| John \|
	\| Lily \|
	\| Susan \|
	\| Thomas \|
	\| Tom \|
	\| LiMing \|
	+--------+
	9 rows in set (0.00 sec)

	mysql> select * from tb_students_info where exists (select course_name from tb_course where id = 1);
	+----+--------+------+--------+-----------+------+
	\| id \| name \| age \| height \| course_id \| sex \|
	+----+--------+------+--------+-----------+------+
	\| 1 \| Dany \| 25 \| 160 \| 1 \| M \|
	\| 2 \| Green \| 23 \| 158 \| 2 \| M \|
	\| 3 \| Henry \| 23 \| 185 \| 1 \| W \|
	\| 4 \| Jane \| 22 \| 162 \| 3 \| M \|
	\| 5 \| Jim \| 24 \| 175 \| 2 \| W \|
	\| 6 \| John \| 21 \| 172 \| 4 \| W \|
	\| 7 \| Lily \| 22 \| 165 \| 4 \| M \|
	\| 8 \| Susan \| 23 \| 170 \| 5 \| M \|
	\| 9 \| Thomas \| 22 \| 178 \| 5 \| W \|
	\| 10 \| Tom \| 23 \| 165 \| 5 \| W \|
	\| 11 \| LiMing \| 22 \| 180 \| 7 \| M \|
	+----+--------+------+--------+-----------+------+
	11 rows in set (0.00 sec)

	#查询tb_course表中是否存在课程id为1的课程，如果有救查询tb_students_info表中age=22的记录
	mysql> select * from tb_students_info where age = 22 and exists (select course_name from tb_course where id = 1);
	+----+--------+------+--------+-----------+------+
	\| id \| name \| age \| height \| course_id \| sex \|
	+----+--------+------+--------+-----------+------+
	\| 4 \| Jane \| 22 \| 162 \| 3 \| M \|
	\| 7 \| Lily \| 22 \| 165 \| 4 \| M \|
	\| 9 \| Thomas \| 22 \| 178 \| 5 \| W \|
	\| 11 \| LiMing \| 22 \| 180 \| 7 \| M \|
	+----+--------+------+--------+-----------+------+
	4 rows in set (0.00 sec)

	mysqldump [OPTIONS] database [tables ...]
	mysqldump [OPTIONS] --all-databases [OPTIONS]
	mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...]

zic师傅

呐！现在开始要放晴了哦！

念两句诗

mysql进阶

mysql进阶

1.安装mysql

1.1 mysql二进制安装

1.2 mysql破解密码

2.mysql配置文件

3.多表联查

3.1 什么是多表联查

3.2 交叉连接(CROSS JOIN)

3.2.1 笛卡尔积

3.2.2 交叉连接

3.3 内连接

3.4 外连接

3.4.1 左连接

3.4.2 右连接

3.5 分组查询

3.5.1 group by 单独使用

3.5.2 group by 与 group_concat()

3.5.3 group by 与函数聚合

3.5.4 group by 与 with rollup

3.6 子查询

3.6.1 in | not in

3.6.2 exists | not exists

4.mysql数据库备份与恢复

4.1 数据库常用备份方案

4.2 mysql备份工具mysqldump

4.3 mysql数据库恢复

4.4 差异备份与恢复

4.4.1 mysql差异备份

4.2.2 mysql差异备份恢复

4.2.3 使用二进制日志进行恢复备份

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常用链接

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	-uUSERNAME 指定数据库用户名
	-hHOST 指定服务器主机，请使用ip地址
	-pPASSWORD 指定数据库用户的密码
	-P# 指定数据库监听的端口，这里的#需用实际的端口号代替，如-P3307

	mysql> show databases;
	+--------------------+
	\| Database \|
	+--------------------+
	\| information_schema \|
	\| mysql \|
	\| performance_schema \|
	\| sys \|
	\| zzd \|
	+--------------------+
	5 rows in set (0.00 sec)

	mysql> use zzd;
	Database changed
	mysql> show tables;
	+------------------+
	\| Tables_in_zzd \|
	+------------------+
	\| tb_course \|
	\| tb_students_info \|
	+------------------+
	2 rows in set (0.01 sec)


	[root@zzd139 ~]# ls
	anaconda-ks.cfg pass
	[root@zzd139 ~]# mysqldump --all-databases > all-`date +%Y-%m-%d:%H:%M:%S`.sql
	[root@zzd139 ~]# ls
	all-2022-07-28:21:26:56.sql anaconda-ks.cfg pass
	$(这里mysqldump命令需要带上用户和密码，mysqldump -uroot -pxxxxx。因为麻烦和安全性考虑，可以编写文件.my.cnf文件针对与mysqldump命令不需要每次都输入密码和用户)
	[root@zzd139 ~]# vim ~/.my.cnf
	[mysqldump]
	user=root
	host=localhost
	password=xxxxx
	$(下列4行是为了登录mysql不需要输入密码和用户的配置)
	[client]
	user=root
	host=localhost
	password=xxxxx
	[root@zzd139 ~]# systemctl restart mysqld.service

	[root@zzd139 ~]# mysqldump zzd tb_students_info tb_course > db_zzd-tables-`date +%Y-%m-%d:%H:%M:%S`.sql
	[root@zzd139 ~]# ls
	all-2022-07-28:21:26:56.sql anaconda-ks.cfg db_zzd-tables-2022-07-28:21:41:04.sql pass

	[root@zzd139 ~]# mysqldump --databases zzd > db_zzd-`date +%Y-%m-%d:%H:%M:%S`.sql
	[root@zzd139 ~]# ls
	all-2022-07-28:21:26:56.sql anaconda-ks.cfg db_zzd-2022-07-28:21:42:06.sql db_zzd-tables-2022-07-28:21:41:04.sql pass

	#模拟误删数据库zzd
	mysql> drop database zzd;
	Query OK, 2 rows affected (0.01 sec)

	mysql> show databases;
	+--------------------+
	\| Database \|
	+--------------------+
	\| information_schema \|
	\| mysql \|
	\| performance_schema \|
	\| sys \|
	+--------------------+
	4 rows in set (0.00 sec)

	#恢复数据库zzd
	[root@zzd139 ~]# mysql < db_zzd-2022-07-28:21:42:06.sql

	mysql> show databases;
	+--------------------+
	\| Database \|
	+--------------------+
	\| information_schema \|
	\| mysql \|
	\| performance_schema \|
	\| sys \|
	\| zzd \|
	+--------------------+
	5 rows in set (0.00 sec)

	#恢复zzd数据库的tb_students_info表和tb_course表
	mysql> use zzd;
	Database changed

	mysql> source db_zzd-tables-2022-07-28:21:41:04.sql
	Query OK, 0 rows affected (0.00 sec)
	………
	Query OK, 0 rows affected (0.00 sec)

	mysql> show tables;
	+------------------+
	\| Tables_in_zzd \|
	+------------------+
	\| tb_course \|
	\| tb_students_info \|
	+------------------+
	2 rows in set (0.00 sec)

	mysql> select * from tb_course;
	+----+-------------+
	\| id \| course_name \|
	+----+-------------+
	\| 1 \| Java \|
	\| 2 \| MySQL \|
	\| 3 \| Python \|
	\| 4 \| Go \|
	\| 5 \| C++ \|
	\| 6 \| HTML \|
	+----+-------------+
	6 rows in set (0.00 sec)

	[root@zzd139 ~]# vim /etc/my.cnf
	server-id = 1
	log-bin = mysql_bin
	[root@zzd139 ~]# systemctl restart mysqld.service

	[root@zzd139 ~]# mysqldump --single-transaction --flush-logs --master-data=2 --all-databases --delete-master-logs > all-`date +%Y-%m-%d:%H:%M:%S`.sql
	[root@zzd139 ~]# ls all-2022-07-28\:22\:10\:32.sql
	all-2022-07-28:22:10:32.sql

	#增加新内容
	[root@zzd139 ~]# mysql
	Welcome to the MySQL monitor. Commands end with ; or \g.
	Your MySQL connection id is 3
	Server version: 5.7.38-log MySQL Community Server (GPL)

	Copyright (c) 2000, 2022, Oracle and/or its affiliates.

	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>use zzd;
	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> insert into tb_course(course_name) values('C#'),('PHP');
	Query OK, 2 rows affected (0.01 sec)
	Records: 2 Duplicates: 0 Warnings: 0

	mysql> select * from tb_course;
	+----+-------------+
	\| id \| course_name \|
	+----+-------------+
	\| 1 \| Java \|
	\| 2 \| MySQL \|
	\| 3 \| Python \|
	\| 4 \| Go \|
	\| 5 \| C++ \|
	\| 6 \| HTML \|
	\| 7 \| C# \|
	\| 8 \| PHP \|
	+----+-------------+
	8 rows in set (0.00 sec)

	mysql> drop database zzd;
	Query OK, 2 rows affected (0.00 sec)

	mysql> show databases;
	+--------------------+
	\| Database \|
	+--------------------+
	\| information_schema \|
	\| mysql \|
	\| performance_schema \|
	\| sys \|
	+--------------------+
	4 rows in set (0.00 sec)

	[root@zzd139 ~]# ll /opt/mysql/data/
	total 123052
	-rw-r-----. 1 mysql mysql 56 Jul 27 17:09 auto.cnf
	-rw-------. 1 mysql mysql 1680 Jul 27 17:09 ca-key.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 ca.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 client-cert.pem
	-rw-------. 1 mysql mysql 1676 Jul 27 17:09 client-key.pem
	-rw-r-----. 1 mysql mysql 390 Jul 28 22:05 ib_buffer_pool
	-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:20 ibdata1
	-rw-r-----. 1 mysql mysql 50331648 Jul 28 22:20 ib_logfile0
	-rw-r-----. 1 mysql mysql 50331648 Jul 27 17:09 ib_logfile1
	-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:10 ibtmp1
	drwxr-x---. 2 mysql mysql 4096 Jul 27 17:09 mysql
	-rw-r-----. 1 mysql mysql 581 Jul 28 22:20 mysql_bin.000002
	-rw-r-----. 1 mysql mysql 19 Jul 28 22:10 mysql_bin.index
	-rw-r-----. 1 mysql mysql 5 Jul 28 22:05 mysql.pid
	drwxr-x---. 2 mysql mysql 8192 Jul 27 17:09 performance_schema
	-rw-------. 1 mysql mysql 1680 Jul 27 17:09 private_key.pem
	-rw-r--r--. 1 mysql mysql 452 Jul 27 17:09 public_key.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 server-cert.pem
	-rw-------. 1 mysql mysql 1676 Jul 27 17:09 server-key.pem
	drwxr-x---. 2 mysql mysql 8192 Jul 27 17:09 sys
	-rw-r-----. 1 mysql mysql 92152 Jul 28 22:05 zzd139.err
	#刷新创建新的二进制日志
	[root@zzd139 ~]# mysqladmin -uroot -p flush-logs
	Enter password:
	[root@zzd139 ~]# ll /opt/mysql/data/
	total 123056
	-rw-r-----. 1 mysql mysql 56 Jul 27 17:09 auto.cnf
	-rw-------. 1 mysql mysql 1680 Jul 27 17:09 ca-key.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 ca.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 client-cert.pem
	-rw-------. 1 mysql mysql 1676 Jul 27 17:09 client-key.pem
	-rw-r-----. 1 mysql mysql 390 Jul 28 22:05 ib_buffer_pool
	-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:23 ibdata1
	-rw-r-----. 1 mysql mysql 50331648 Jul 28 22:23 ib_logfile0
	-rw-r-----. 1 mysql mysql 50331648 Jul 27 17:09 ib_logfile1
	-rw-r-----. 1 mysql mysql 12582912 Jul 28 22:10 ibtmp1
	drwxr-x---. 2 mysql mysql 4096 Jul 27 17:09 mysql
	-rw-r-----. 1 mysql mysql 628 Jul 28 22:23 mysql_bin.000002
	-rw-r-----. 1 mysql mysql 154 Jul 28 22:23 mysql_bin.000003
	-rw-r-----. 1 mysql mysql 38 Jul 28 22:23 mysql_bin.index
	-rw-r-----. 1 mysql mysql 5 Jul 28 22:05 mysql.pid
	drwxr-x---. 2 mysql mysql 8192 Jul 27 17:09 performance_schema
	-rw-------. 1 mysql mysql 1680 Jul 27 17:09 private_key.pem
	-rw-r--r--. 1 mysql mysql 452 Jul 27 17:09 public_key.pem
	-rw-r--r--. 1 mysql mysql 1112 Jul 27 17:09 server-cert.pem
	-rw-------. 1 mysql mysql 1676 Jul 27 17:09 server-key.pem
	drwxr-x---. 2 mysql mysql 8192 Jul 27 17:09 sys
	-rw-r-----. 1 mysql mysql 92152 Jul 28 22:05 zzd139.err

	[root@zzd139 ~]# mysql < all-2022-07-28\:22\:10\:32.sql
	[root@zzd139 ~]# mysql -e 'show databases;'
	+--------------------+
	\| Database \|
	+--------------------+
	\| information_schema \|
	\| mysql \|
	\| performance_schema \|
	\| sys \|
	\| zzd \|
	+--------------------+

	[root@zzd139 ~]# mysql -e 'show tables from zzd;'
	+------------------+
	\| Tables_in_zzd \|
	+------------------+
	\| tb_course \|
	\| tb_students_info \|
	+------------------+

	[root@zzd139 ~]# mysql -e 'select * from zzd.tb_course;'
	+----+-------------+
	\| id \| course_name \|
	+----+-------------+
	\| 1 \| Java \|
	\| 2 \| MySQL \|
	\| 3 \| Python \|
	\| 4 \| Go \|
	\| 5 \| C++ \|
	\| 6 \| HTML \|
	+----+-------------+