Mysql usage skills and experience

This article is for personal notes only

• Mysql user operation
  
  • Query all current users/IP/passwords:
    use mysql;
    select user,host,password from user;
  • Refresh user table permissions (required to run when modifying users or user permissions): FLUSH privileges;
  • 添加用户：CREATE USER ‘username’@’host’ IDENTIFIED BY ‘password’;（例： CREATE USER ‘test’@’localhost’ IDENTIFIED BY ‘test’;）
  • Authorize users: GRANT privileges ON databasename.tablename TO 'username'@'host'; (Example: GRANT privileges ON mysql.user TO 'test'@'localhost';)
  • Authorize all privileges to the user: GRANT ALL privileges ON . TO 'username'@'host'; (Example: GRANT ALL privileges ON . TO 'test'@'localhost';)
  • 撤销用户权限：REVOKE privilege ON databasename.tablename FROM ‘username’@’host’;（例： REVOKE privilege ON mysql.user FROM ‘test’@’localhost’;）
  • View all permissions of the current user: SHOW grants FOR 'username'@'host'; (Example: SHOW grants FOR 'test'@'localhost';)
  • Change user password: SET PASSWORD FOR 'username'@'host' = PASSWORD('newpassword'); (Example: SET PASSWORD FOR 'test'@'localhost' = PASSWORD('test'); )
  • To change the root user password when the root password is forgotten:
  • First stop the mysql service service mysql stop
  • Open a new window and run mysqld_safe –skip-grant-tables& (open mysql safe mode)
  • Run mysql in another window (login mysql)
  • 在mysql命令行中运行 use mysq; update user set password=password(‘password’) where user = ‘username’;（例：update user set password=password(‘root’) where user = ‘root’;）
  • Delete user: DROP USER 'username'@'host'; (Example: DROP USER 'test'@'localhost';)
• Mysql data backup
  
  • Only import table structure: mysqldump –opt -d dbname -u username -p > BackupName.sql (example: mysqldump –opt -d test -uroot -p > BackupName.sql)
  • 整库备份：mysqldump -u username -p –all-databases > BackupName.sql （例：mysqldump -uroot -p –all-databases > all.sql）
  • 多库备份：mysqldump -u username -p –databases dbname1 dbname2 …-> BackupName.sql（例： mysqldump -uroot -p –databases mysql test > all.sql）
  • Single database backup: mysqldump -u username -p dbname > BackupName.sql (Example: mysqldump -uroot -p mysql > mysql.sql)
  • 多表备份：mysqldump -u username -p –databases dbname –tables tablename1 tablename2 …> BackupName.sql（例：mysqldump -root -p –databases test –tables tablename1 tablename2 > all.sql）
  • Single table backup: mysqldump -u username -p dbname tablename > BackName.sql (example: mysqldump -uroot -p test tablename1 > all.sql)
• Mysql data import
  
  • source ** .sql (Example: source /tmp/test.sql, if the sql file includes the creation of the database, you do not need to select the database, if not, you need to select the database first)
• Mysql csv related
  
  • 导出csv文件：select 字段名1,字段名2.. from dbname.tablename into outfile ‘BackupName.csv’ fields terminated by ‘,’ optionally enclosed by ” lines terminated by ‘/n’;（例：select user,host,password from user into outfile ‘/tmp/test.sql’ fields terminated by ‘,’ optionally enclosed by ” lines terminated by ‘/n’;）
    
  • Unable to export file
  • Run SHOW VARIABLES LIKE "secure_file_priv"; view output folder
    
  • View output folders
    
    • If the returned result is empty or you want to change the export directory, you need to change the mysql configuration. The default configuration file of mysql is in /etc/my.cnf. You can check whether there is a secure_file_priv option. If so, you can change it directly. If not, you need to add secure_file_priv=output Folder (for example: secure_file_priv=/tmp/), if you change the configuration, you need to restart mysql.
  • 导入csv文件：load data local infile ‘BackupName.csv’ into table tablename fields terminated by ‘,’ lines terminated by ‘/n’(first_name,last_name,email);
• Common Commands and Techniques
  
  • Default configuration file address: /etc/my.cnf
  • Show all databases: show tables
  • Selected library: use library name (eg: use mysql)
  • Show all tables of the currently selected library: show tables
  • Display all field descriptions of a table: desc table name (for example: desc user)
  • Show master table status: show master status
  • Show slave table status: show slave status