Shulou(Shulou.com)06/02 Report--

Database (Database) is a warehouse built on computer storage equipment, which organizes, stores and manages data according to the data structure.

To put it simply, it can be regarded as an electronic filing cabinet-the place where electronic documents are stored, and users can add, intercept, update, delete and other operations on the data in the documents.

First, install and deploy http://www.daiqiyang.com

# the database is installed by default. If not, use the following command to install it

[root@mail ~] # yum install-y mariadb

# start the database service

[root@mail ~] # systemctl restart mariadb

# initialize the database

[root@mail ~] # mysql_secure_installation enter directly here for the first time: set the password for the root of the database: make some initialization settings later, and generally choose Y.

# add a permanent permit policy to the firewall

[root@mail] # firewall-cmd-- permanent-- add-service=mysql

# reload firewall configuration

[root@mail] # firewall-cmd-- reload

Second, login and use

# logging in to the database system

[root@mail ~] # mysql-uroot-predhat / / Note there is no space between commands and parameters [root@mail ~] # mysql-uroot-p / / so that the login can hide the password [root@mail ~] # mysql-uroot-h localhost-p [DATABASE NAME]

-u: the user name that connects to the mysql server

-ip address or hostname of the h:mysql server

-p: password to connect to the mysql server

# check how many databases the system has

MariaDB [(none)] > show databases; / / commands in the database all end with;

# exit the database system

MariaDB [(none)] > quitMariaDB [(none)] > exit

# create a database

MariaDB [(none)] > create database luntan

# switch to a database

MariaDB [mysql] > use mysql

# View the tables in the database

MariaDB [mysql] > show tables

# View the table structure of the data table

MariaDB [mysql] > desc user

# query some data in the user table

MariaDB [mysql] > select host,user,password from user

# create a table

MariaDB [mysql] > create table person (- > number int (11),-> name varchar (255),-> birthday date)

# query the table structure of the created table

MariaDB [mysql] > desc person

# insert a few pieces of data

MariaDB [mysql] > insert into person (number,name,birthday) values (1, "", 20191225); MariaDB [mysql] > insert into person (number,name,birthday) values (2, "xixi", 20191226); MariaDB [mysql] > insert into person (number,name,birthday) values (3, "hehe", 20191227)

# query table contents

MariaDB [mysql] > select * from person

# delete the contents of the table

MariaDB [mysql] > delete from person where name= ""; MariaDB [mysql] > delete from person where number=3

# update the data in the table

MariaDB [mysql] > update person set name= "" where name= "xixi"; MariaDB [mysql] > update person set number=1 where birthday=20191226

Management of users and control of access rights

Create a database login user

MariaDB [mysql] > create user xiaoming@localhost identified by 'redhat';MariaDB [mysql] > create user xiaohong@localhost identified by "redhat"; MariaDB [mysql] > select host,user,password from user

View current users:

MariaDB [none)] > select user ()

View the current user's database:

MariaDB [none)] > select database ()

Log in to the database using the Xiaoming user:

[root@localhost] # mysql-u xiaoming-p

# View databases that can be accessed

MariaDB [(none)] > show databases

# the right to log in to a table as a root user to a xiaoming user

MariaDB [(none)] > grant select,update,insert,delete on mysql.person to xiaoming@localhost

Exit the database system and log in again using the xiaoming user

[root@localhost ~] # mysql-u xiaoming-pMariaDB [(none)] > use mysql

# testing various permissions

MariaDB [mysql] > select * from person;MariaDB [mysql] > insert person (number,name,birthday) value (3, "xiaoming", 20181228); MariaDB [mysql] > update person set name= "xixi" where number=1MariaDB [mysql] > delete from person where number=1

# Log in with root user and change the permissions of xiaoming user

MariaDB [(none)] > revoke delete on mysql.person from xiaoming@localhost

# use select statement to delete table data to confirm that permissions have been disabled

MariaDB [mysql] > delete from person where number=3

IV. Backup and restore

Back up all tables in the entire database

[root@mail ~] # mysqldump-u root-p mysql > / mysql_backup_20160510.dump / / make a backup file, location can be selected

# use root users to log in to the database and delete the person table

MariaDB [mysql] > drop table person

# exit the system and perform a restore operation

[root@mail] # mysql-u root-p mysql

Select * from person

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Copyright notice: this article is the original article of CSDN blogger "pessimistic optimist", in accordance with the copyright agreement of CC 4.0BY-SA. Please attach the original source link and this statement for reprint.

Original link: https://blog.csdn.net/weixin_43997530/article/details/103634828

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