数据对于企业的重要性，不言而喻。所以在使用Mysql数据库的过程中，经常需要使用到数据库的备份和导出功能，非常重要！！！
物理备份:对数据库操作系统的物理文件(如数据文件、日志文件等)
冷备份(脱机备份) :是在关闭数据库的时候进行的热备份(联机备份) :数据库处于运行状态，依赖于数据库的日志文件温备份:数据库锁定表格(不可写入但可读)的状态下进行备份操作逻辑备份:对数据库逻辑组件(如: 表等数据库对象)的 备份 从数据库的备份策略角度，备份可分为
完全备份：每次对数据进行完整的备份差异备份：备份那些自从上次完全备份之后被修改过的文件增量备份：只有那些在上次完全备份或者增量备份后被修改的文件才会被备份在生产环境中，数据的安全性至关重要 任何数据的丢失都可能产生严重的后果: 2.1：造成数据丢失的原因
程序错误人为操作错误运算错误磁盘故障灾难（如火灾、地址）和盗窃完全备份是对整个数据库的备份、数据库结构和文件结构的备份 完全备份保存的是备份完成时刻的数据库 完全备份是增量备份的基础
安全性高 备份与恢复操作简单方便
数据存在大量的重复 占用大量的备份空间，空间利用率低 备份与恢复时间长
关闭MySQL数据库 使用tar命令直接打包数据库文件夹 直接替换现有MySQL目录即可
mysql> use tom; Database changed mysql> create table chengji (name VARCHAR(10),point INT(10)); Query OK, 0 rows affected (0.02 sec) mysql> desc chengji; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(10) | YES | | NULL | | | point | int(10) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.01 sec) mysql> insert into chengji values('xiaowang',77),('xiaoli',75); Query OK, 2 rows affected (0.01 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select * from chengji -> ; +----------+-------+ | name | point | +----------+-------+ | xiaowang | 77 | | xiaoli | 75 | +----------+-------+ 2 rows in set (0.00 sec) 先关闭数据库服务，再打包备份 [root@server3 ~]# tar zcf /backup/mysql_all-$(date +%F).tar.gz /usr/local/mysql/data/ tar: 从成员名中删除开头的“/” [root@server3 ~]# cd /backup/ [root@server3 backup]# ll 总用量 1376 -rw-r--r--. 1 root root 1406517 10月 13 14:48 mysql_all-2020-10-13.tar.gz 将原来的数据移走到备份文件夹中，解压刚才备份的tar包到/restore目录下，再移动到mysql服务的文件夹中 [root@server1 ~]# mkdir bak [root@server1 ~]# mv /usr/local/mysql/data/ /bak #将数据库的文件移动至/bak文件夹中 [root@server1 ~]# mkdir restore [root@server1 ~]# tar zxf /backup/mysql_all-2020-10-23.tar.gz -C restore [root@server1 ~]# mv restore/usr/local/mysql/data/ /usr/local/mysql/ #将之前备份的文件移动至mysql服务的文件夹中 重启mysql服务，登录mysql，查看数据是否恢复 mysql> use tom; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select * from chengji; +----------+-------+ | name | point | +----------+-------+ | xiaowang | 77 | | xiaoli | 75 | +----------+-------+ 2 rows in set (0.00 sec)MySQL自带的备份工具，可方便实现对MySQL的备份 可以将指定的库、表导出为SQL脚本 使用命令mysql导入备份的数据
mysqldump -u root -p --all-databses > all-data-$(date +%F).sql ###备份所有数据库 mysqldump -u root -p -databases auth mysql > auth-mysql.sql ###备份auth和mysql库 mysqldump -u root -p auth > auth-$(data +%F).sql ###备份auth数据库 mysqldump -u root -p mysql user > mysql-user-$(date +%F).sql ###备份mysql的user表 mysqldump -u root -p -d mysql user > /tmp/desc-mysql-user.sql ###备份mysql库user表的结构 mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | myadm | | mysql | | performance_schema | | student | | sys | | tom | +--------------------+ 7 rows in set (0.00 sec) [root@server3 opt]# mysqldump -u root -p tom > /opt/tom.sql Enter password: [root@server3 opt]# ls tom.sql # 导出的备份文件示例：
mysql> use tom; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | chengji | +---------------+ 1 row in set (0.00 sec) mysql> select * from chengji; +----------+-------+ | name | point | +----------+-------+ | xiaowang | 77 | | xiaoli | 75 | +----------+-------+ 2 rows in set (0.00 sec) #复制tom表 name字段 张三内容 生成一张新表pp mysql> create table pp as select * from chengji where name='xiaowang'; Query OK, 1 row affected (0.03 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | chengji | | pp | +---------------+ 2 rows in set (0.00 sec) #新生成表 mysql> select *from pp; +----------+-------+ | name | point | +----------+-------+ | xiaowang | 77 | +----------+-------+ 1 row in set (0.00 sec) [root@server3 ~]# mysql -u root -p123123 chengji pp > /opt/pp.sql mysql: [Warning] Using a password on the command line interface can be insecure. [root@server3 ~]# ls /opt pp.sqlsource命令【作用于mysql模式下】
mysql命令【作用于于linux模式下】
登录到mysql数据库
执行source备份sql脚本的路径
source恢复的示例
MYSQL[(none)]> source /backup/all-data.sql模拟删除表
mysql> use tom; Database changed #删除表 mysql> drop table chengji; Query OK, 0 rows affected (0.02 sec) mysql> drop table pp; Query OK, 0 rows affected (0.01 sec)进行恢复
mysql> use tom; Database changed mysql> use tom; Database changed mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | tom | +---------------+ 1 row in set (0.00 sec) mysql> select * from tom; +----+----------+----------+ | id | name | address | +----+----------+----------+ | 1 | zhangsan | hangzhou | +----+----------+----------+ 1 row in set (0.00 sec) mysql> insert into tom (name,address) values('lisi','wuxi'); Query OK, 1 row affected (0.00 sec) mysql> select * from tom; +----+----------+----------+ | id | name | address | +----+----------+----------+ | 1 | zhangsan | hangzhou | | 2 | lisi | wuxi | +----+----------+----------+ 2 rows in set (0.00 sec) mysql> create table pp as select * from tom where name='zhangsan'; Query OK, 1 row affected (0.02 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | pp | | tom | +---------------+ 2 rows in set (0.00 sec) mysql> select * from pp; +----+----------+----------+ | id | name | address | +----+----------+----------+ | 1 | zhangsan | hangzhou | +----+----------+----------+ 1 row in set (0.00 sec) mysql> Ctrl-C -- exit! Aborted [root@server3 opt]# mysqldump -u root -p tom pp > /opt/pp.sql Enter password: [root@server3 opt]# ls /opt/ all.sql opt.sql pp.sql rh tom.tom [root@server3 opt]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 11 Server version: 5.6.36-log Source distribution Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> drop table tom; ERROR 1046 (3D000): No database selected mysql> use tom; 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> drop table tom; Query OK, 0 rows affected (0.01 sec) mysql> drop table pp; Query OK, 0 rows affected (0.00 sec) ```java mysql> show tables; Empty set (0.00 sec) #恢复 mysql> source /opt/all.sql; ..省略内容 mysql> use tom; Database changed mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | tom | +---------------+ 1 row in set (0.00 sec) mysql> source /opt/pp.sql; mysql> show tables; +---------------+ | Tables_in_tom | +---------------+ | pp | | tom | +---------------+ 2 rows in set (0.00 sec) mysql> select * from pp; +----+----------+----------+ | id | name | address | +----+----------+----------+ | 1 | zhangsan | hangzhou | +----+----------+----------+ 1 row in set (0.00 sec) #已经恢复 这边我们是恢复所有数据库 #也可以单独的对标进行备份恢复备份数据中有重复数据 备份时间与恢复时间长
优点： 没有重复数据，效率高，空间利用率最大化 备份量不大，时间短 缺点： 恢复麻烦：需要上次完全备份及完全备份之后所有的增量备份才能恢复，而且要对所有增量备份进行逐个反推恢复 安全性较低
MySQL没有提供直接的增量备份方法 可以通过 MySQL提供的二进制日志（ binary logs）间接实现增量备份 二进制日志保存了所有更新或者可能更新数据库的操作 二进制日志在启动MySQL服务器后开始记录，并在文件达到 max_binlog_size所设置的大小或者接收到flush logs命令后重新 创建新的日志文件 只需定时执行flush logs方法重新创建新的日志，生成二进制文 件序列，并及时把这些日志保存到安全的地方就完成了一个时间 段的增量备份
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