MySQL-底层设置

目录

一、字符集

1.1、字符集设置

1.2、各级别的字符集

二、大小写规范

2.1、查看系统设置

三、mysql数据目录(linux)

四、用户与权限管理

五、角色（mysql8.0有）

---

一、字符集

1.1、字符集设置

• 查看数据库字符集

  show create database table_name;
  show variables like 'character_%';

• 查看数据库比较级

  show variables like 'collation_%';

• 修改字符集(mysql8.0不需要修改，默认字符集为utf-8)
• 查看mysql安装目录

  select @@datadir;
  select @@basedir;

• 修改配置文件 查看my.cnf应该存在的位置

  mysql --help|grep 'my.cnf'

• mac版本默认没有my.cnf配置文件，可以找一个配置文件，将配置文件拷贝到上面查到的目录中的一个地址

  # Example MySQL config file for small systems.  
  #  
  # This is for a system with little memory (<= 64M) where MySQL is only used  
  # from time to time and it's important that the mysqld daemon  
  # doesn't use much resources.  
  #  
  # MySQL programs look for option files in a set of  
  # locations which depend on the deployment platform.  
  # You can copy this option file to one of those  
  # locations. For information about these locations, see:  
  # http://dev.mysql.com/doc/mysql/en/option-files.html  
  #  
  # In this file, you can use all long options that a program supports.  
  # If you want to know which options a program supports, run the program  
  # with the "--help" option.  
  
  # The following options will be passed to all MySQL clients  
  [client]  
  default-character-set=utf8  
  #password   = your_password  
  port        = 3306 
  socket      = /tmp/mysql.sock  
  
  # Here follows entries for some specific programs  
  
  # The MySQL server   
  [mysqld]  
  default-storage-engine=INNODB  
  character-set-server=utf8  
  collation-server=utf8_general_ci  
  port        = 3306 
  socket      = /tmp/mysql.sock  
  skip-external-locking  
  key_buffer_size = 16K  
  max_allowed_packet = 1M  
  table_open_cache = 4 
  sort_buffer_size = 64K  
  read_buffer_size = 256K  
  read_rnd_buffer_size = 256K  
  net_buffer_length = 2K  
  thread_stack = 128K  
  
  # Don't listen on a TCP/IP port at all. This can be a security enhancement,  
  # if all processes that need to connect to mysqld run on the same host.  
  # All interaction with mysqld must be made via Unix sockets or named pipes.  
  # Note that using this option without enabling named pipes on Windows  
  # (using the "enable-named-pipe" option) will render mysqld useless!  
  #   
  #skip-networking  
  server-id   = 1
  
  # Uncomment the following if you want to log updates  
  log-bin=mysql-bin  
  
  # binary logging format - mixed recommended  
  #binlog_format=mixed  
  
  # Causes updates to non-transactional engines using statement format to be  
  # written directly to binary log. Before using this option make sure that  
  # there are no dependencies between transactional and non-transactional  
  # tables such as in the statement INSERT INTO t_myisam SELECT * FROM  
  # t_innodb; otherwise, slaves may diverge from the master.  
  #binlog_direct_non_transactional_updates=TRUE  
  
  # Uncomment the following if you are using InnoDB tables  
  #innodb_data_home_dir = /usr/local/mysql/data  
  #innodb_data_file_path = ibdata1:10M:autoextend  
  #innodb_log_group_home_dir = /usr/local/mysql/data  
  # You can set .._buffer_pool_size up to 50 - 80 %  
  # of RAM but beware of setting memory usage too high  
  #innodb_buffer_pool_size = 16M  
  #innodb_additional_mem_pool_size = 2M  
  # Set .._log_file_size to 25 % of buffer pool size  
  #innodb_log_file_size = 5M  
  #innodb_log_buffer_size = 8M  
  #innodb_flush_log_at_trx_commit = 1 
  #innodb_lock_wait_timeout = 50 
  
  [mysqldump]  
  quick  
  max_allowed_packet = 16M  
  
  [mysql]  
  no-auto-rehash  
  # Remove the next comment character if you are not familiar with SQL  
  #safe-updates  
  
  [myisamchk]  
  key_buffer_size = 8M  
  sort_buffer_size = 8M  
  
  [mysqlhotcopy]  
  interactive-timeout
  
  [mysqld] 
  transaction-isolation=READ-COMMITTED

• 修改文件权限，不然启动会报错

  sudo chmod 664 my.cnf    

• 重新启动mysql，启动失败的话就重新启动一下电脑；

  systemctl restart mysqld;

• 登录mysql，执行

  show variables like 'character_%';

• mysql字符修改成功
• 修改数据库或表字符

  alter database database_name charset utf8;
  alter table table_name charset utf8;

• 查看数据库和表字符

  show create database database_name;
  show create table table_name;

1.2、各级别的字符集

MySQL有4个级别的字符集和比较规则，分别是：

• 服务器级别；
• 数据库级别；
• 表级别；
• 列级别；

注意：创建数据库表或者列时可以在后面增加一个charcter set来指定字符集，mysql8默认是utf-8。客户端编码必须和服务器character_set_client一致，解码必须和服务器character_set_results一致。

二、大小写规范

2.1、查看系统设置

show variables like '%lower_case_table_name%';

# 5.7版本下修改：在my.cnf文件下[mysqld]下增加然后重启服务器
lower_case_table_names=1

#8.0版本下修改：
停止mysql服务；
删除数据目录 
/var/lib/mysql 目录
在mysql配置文件 my.cnf中添加 lower_case_table_names=1
启动服务器。

• 0（默认）：大小写敏感；
• 1：大小写不敏感，sql语句和数据库表都是以小写形式存储在磁盘上；
• 2：创建的表和数据库依据语句上格式存放，凡是查找都是转换为小写进行。

三、mysql数据目录(linux)

四、用户与权限管理

-- 创建用户
create user 'kanlina' identified by '123456';
create user 'kanlina'@'localhost' identified by '123456';

-- 修改用户
update mysql.user set user = 'kanlina1' where user = 'kanlina';
flush privileges;

-- 删除用户
drop user 'kanlina1';
drop user 'kanlina'@'localhost';
-- 设置当前用户密码 以下@'localhost'可省略
alter user user() identified by '123456';
set password = ******; -- mysql 8.0取消 

-- 修改其他用户密码
alter user '用户名'@'localhost' identified by '密码';
set password for '用户名'@'hostname'='密码';

-- 密码过期策略
alter user 'kanlina'@'localhost' password expire; 

-- 设置过期时间
create user 'kanlina'@'localhost' password expire interval 90 day;
alter user 'kanlina'@'localhost' password expire interval 90 day;
-- 永不过期
create user 'kanlina'@'localhost' password expire interval never;
alter user 'kanlina'@'localhost' password expire interval never;
-- 延用全局过期策略
create user 'kanlina'@'localhost' password expire interval default;
alter user 'kanlina'@'localhost' password expire interval default;
-- 或者配置文件中加入
default_password_lifetime

-- 密码重用策略 
set persist password_history = 6; #设置不能选择最近使用过的6个密码
set persist password_reuse_interval = 365; #设置不能选择最近一年内的密码
-- 系统变量设置密码
password_history --规定密码重用数量
password_reuse_interval --规定密码重用的周期

-- 授予权限
grant 权限1,权限2,...权限n on 数据库名称.表名称 to 用户名@用户地址 [identified by '密码口令']; #如果没有该用户则创建新用户 
grant select,update,delete,insert on test.acc_line_mapping to 'kanlina';
grant all privileges on *.* to 'kanlina'@'%'; #和root权限一样，但是无法赋予其他用户权限

-- 查看权限
show grants;

-- 回收权限
revoke 权限1,权限2,...权限n on 数据库名称.表名称 from '用户名';

五、角色（mysql8.0有）

-- 创建角色
create role 'manager','stoker';

--给角色分配权限
grant privileges on table_name to 'role_name'[@'localhost'];

--查询权限
show privileges\G;

--查看角色的权限
show grants for 'manager'@'%';

--回收角色权限
revoke update on 数据库.表 from '角色名';

--删除角色
drop role '角色名';

--给用户赋予角色
grant '角色名' to '用户';
--激活角色
set default role all to '角色名';

--查询已激活角色
select current_role();

--显示是否永久激活
show variables like 'activate_all_roles_on_login';
--设置永久激活
set global activate_all_roles_on_login=on;