mysql实践总结
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首先介绍mysql的安装和基本使用、进阶操作、讲解mysql的导入导出和自动备份，然后介绍安全模式修改密码和mysql的全文本搜索功能，最后记录了个人使用mysql中遇到的问题集，闲暇时我也会多看几次，巩固下基础吧。
基础使用
sudo apt-get install mysql-common mysql-server
简单使用：建库
CREATE DATABASE IF NOT EXISTS yourdbname DEFAULT CHARSET utf8 COLLATE utf8_general_ci;
建表
create table MyClass(id int(4) not null primary key auto_increment,name char(20) not null,sex int(4) not null default ‘0‘,degree double(16,2));
增加
insert into MyClass values(1,‘Tom‘,96.45),(2,‘Joan‘,82.99), (2,‘Wang‘, 96.59);
删除
delete from MyClass where id=1;
修改
update MyClass set name=‘Mary‘ where id=1;
查询
select * from MyClass;
显示所有视图
select * from information_schema.TABLES where table_type=‘view‘ AND table_schema = ‘数据库名‘;
创建用户
create user xxx identified by ‘password‘;
重命名
rename user aaa to bbb；
删除用户
drop user aaa;
显示权限
show grants for aaa(用户);
授予权限
grant select on xxx(数据库).* to aaa(用户);
授予某个数据库的全部权限
grant all on xxx(数据库).* to aaa(用户);
grant all on xxx(数据库).* to aaa(用户)@localhost;
取消授权
revoke all on *.* from aaa(用户)@localhost;
修改权限
GRANT ALL PRIVILEGES ON *.* TO ‘root‘@‘%’ WITH GRANT OPTION;
以上操作完成之后记得刷新权限：
flush privileges;
导入导出
导出数据和表结构：
mysqldump -uroot -p abc(数据库名) > abc.sql
敲回车后输入密码
只导出表结构
mysqldump -uroot -p -d abc > abc.sql
导入数据库
1、首先建空数据库
mysql> create database abc;
2、导入数据库
mysql -u root -p abc(数据库名) < abc.sql
数据库自动备份
新建备份脚本xxx.sh,输入以下内容
#!/bin/bash # 要备份的数据库名，多个数据库用空格分开 databases=("db1", "db2") # 备份文件要保存的目录，注意当前用户必须用户保存目录的读写权限 basepath=‘/root/backup/mysql/‘ if [ ! -d "$basepath" ]; then mkdir -p "$basepath" fi # 循环databases数组 for db in ${databases[*]} do # 备份数据库生成SQL文件 nice -n 19 /usr/bin/mysqldump -uroot -pcd32d5e86e --database $db > $basepath$db-$(date +%Y%m%d).sql # 将生成的SQL文件压缩 nice -n 19 tar zPcf $basepath$db-$(date +%Y%m%d).sql.tar.gz -C $basepath $db-$(date +%Y%m%d).sql # 删除7天之前的备份数据 find $basepath -mtime +7 -name "*.sql.tar.gz" -exec rm -rf {} \; done # 删除生成的SQL文件 rm -rf $basepath/*.sql
使用crontab设置定时任务，在终端输入crontab -e，加入以下内容，此任务为每天3点自动执行。
0 3 * * * bash xxx.sh(此处填写脚本绝对地址)
开启日志记录
[mysqld] server-id = 1 log_bin = /var/log/mysql/mysql-bin.log max_binlog_size = 1000M binlog-format = row
安全模式操作
进入安全模式修改密码
mysqld_safe --skip-grant-tables & select user,host,password from user where user="root"
不同版本的mysql修改用户密码方式不一样,需要查看mysql->user中的密码字段，如果不是password的话就是authentication_string。
authentication_string的修改方式不太一样：
use mysql; update user set authentication_string=PASSWORD("") where User=‘root‘; update user set plugin="mysql_native_password"; flush privileges; quit; sudo /etc/init.d/mysql stop sudo /etc/init.d/mysql start
如果不是authentication_string，则可用以下方法。
update user set password=PASSWORD("your_password") where user="root" and host=“localhost"
新操作
Mysql全文本搜索
Mysql5.6之后支持InnoDB，中文的全文本搜索，内置使用n-gram为分词处理器，还支持中文～。
创建索引
create fulltext index ngram_idx on tag(Title) with parser ngram;
或
alter table tag add fulltext index ngram_idx(Title) with parser ngram;
获取支持的最小分词长度
SHOW VARIABLES LIKE ‘ft_min_word_len‘; //unix系统可在/etc/my.cnf中修改 [mysqld] ft_min_word_len = 1
开始使用
select Title,match(Title) against(‘清水‘) from tag ;
可能出现的问题集：
- 描述
2017-05-04T01:21:32.004560Z mysqld_safe Logging to ‘/var/log/mysql/error.log‘. 2017-05-04T01:21:32.023009Z mysqld_safe A mysqld process already exists
解决方法：
$ sudo killall mysqld
- 描述
2017-05-04T01:22:26.486677Z mysqld_safe Logging to ‘/var/log/mysql/error.log‘. 2017-05-04T01:22:26.488204Z mysqld_safe Directory ‘/var/run/mysqld‘ for UNIX socket file don‘t exists.
解决方法：
sudo mkdir -p /var/run/mysqld sudo chown -R mysql:mysql /var/run/mysqld
- 描述
$ sudo /etc/init.d/mysql start ies: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory [....] Starting mysql (via systemctl): mysql.servicejob-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
解决方法：
当前文件夹不是实际目录导致
cd到一个实际目录位置即可
- 描述
sudo /etc/init.d/mysql start shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory [....] Starting mysql (via systemctl): mysql.servicejob-working-directory: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
按照提示:See "systemctl status mysql.service" and "journalctl -xe" for details. 但是并么有什么卵用，直接看mysql的log：/var/log/mysql/error.log 2017-05-04T01:37:56.583745Z 0 [Note] InnoDB: Check that you do not already have another mysqld process using the same InnoDB data or log files.
解决方法：
杀掉所有mysqld进程：killall mysqld
再次sudo /etc/init.d/mysql start 成功
- 描述
dpkg被锁定
解决方法
sudo rm /var/cache/apt/archives/lock sudo rm /var/lib/dpkg/lock