数据库大王mysql---linux
一，什么是数据库
关系型数据库
高级excel
非关系型数据库
键值对
二，安装数据库并进行安全初始化
搜索mysql 服务包
shell
[root@mysql ~]# dnf search mysql
Updating Subscription Management repositories.
Unable to read consumer identity
This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.
=================================== Name & Summary Matched: mysql ====================================
mysql.x86_64 : MySQL client programs and shared libraries
apr-util-mysql.x86_64 : APR utility library MySQL DBD driver
dovecot-mysql.x86_64 : MySQL back end for dovecot
mysql-common.x86_64 : The shared files required for MySQL server and client
mysql-errmsg.x86_64 : The error messages files required by MySQL server
mysql-selinux.noarch : SELinux policy modules for MySQL and MariaDB packages
mysql-server.x86_64 : The MySQL server and related files
pcp-pmda-mysql.x86_64 : Performance Co-Pilot (PCP) metrics for MySQL
perl-DBD-MySQL.x86_64 : A MySQL interface for Perl
php-mysqlnd.x86_64 : A module for PHP applications that use MySQL databases
postfix-mysql.x86_64 : Postfix MySQL map support
python3-PyMySQL.noarch : Pure-Python MySQL client library
python3.11-PyMySQL.noarch : Pure-Python MySQL client library
python3.11-PyMySQL+rsa.noarch : Metapackage for python3.11-PyMySQL: rsa extras
python3.12-PyMySQL.noarch : Pure-Python MySQL client library
python3.12-PyMySQL+rsa.noarch : Metapackage for python3.12-PyMySQL: rsa extras
qt5-qtbase-mysql.i686 : MySQL driver for Qt5's SQL classes
qt5-qtbase-mysql.x86_64 : MySQL driver for Qt5's SQL classes
rsyslog-mysql.x86_64 : MySQL support for rsyslog
rubygem-mysql2.x86_64 : A simple, fast Mysql library for Ruby, binding to libmysql
======================================= Summary Matched: mysql =======================================
mariadb-java-client.noarch : Connects applications developed in Java to MariaDB and MySQL databases
mariadb-server-utils.x86_64 : Non-essential server utilities for MariaDB/MySQL applications
perl-DBD-MariaDB.x86_64 : MariaDB and MySQL driver for the Perl5 Database Interface (DBI)安装MySQL服务
shell
[root@mysql ~]# dnf install mysql-server.x86_64 -y
Updating Subscription Management repositories.
Unable to read consumer identity
This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.
AppStream 3.1 MB/s | 3.2 kB 00:00
BaseOS 2.7 MB/s | 2.7 kB 00:00
Dependencies resolved.
======================================================================================================
Package Architecture Version Repository Size
======================================================================================================
Installing:
mysql-server x86_64 8.0.36-1.el9_3 AppStream 17 M
Installing dependencies:验证MySQL服务是否存在并开启服务
shell
[root@mysql ~]# systemctl status mysqld.service #查看服务状态
○ mysqld.service - MySQL 8.0 database server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; preset: disabled)
Active: inactive (dead)
[root@mysql ~]# systemctl start mysqld.service #开启服务
[root@mysql ~]# systemctl status mysqld.service
● mysqld.service - MySQL 8.0 database server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; preset: disabled)
Active: active (running) since Tue 2026-01-13 21:14:35 CST; 6s ago
Process: 30532 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
Process: 30554 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status>
Main PID: 30628 (mysqld)
Status: "Server is operational"
Tasks: 38 (limit: 22944)
Memory: 467.6M
CPU: 3.861s
CGroup: /system.slice/mysqld.service
└─30628 /usr/libexec/mysqld --basedir=/usr
Jan 13 21:14:30 mysql systemd[1]: Starting MySQL 8.0 database server...
Jan 13 21:14:30 mysql mysql-prepare-db-dir[30554]: Initializing MySQL database
Jan 13 21:14:35 mysql systemd[1]: Started MySQL 8.0 database server.
[root@mysql ~]# systemctl enable --now mysqld.service #开机自启
Created symlink /etc/systemd/system/multi-user.target.wants/mysqld.service → /usr/lib/systemd/system/mysqld.service.
[root@mysql ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.36 Source distribution数据库安全初始化
shell
[root@mysql ~]# mysql_secure_installation #安全初始化命令
Securing the MySQL server deployment.
Connecting to MySQL using a blank password.
VALIDATE PASSWORD COMPONENT can be used to test passwords
and improve security. It checks the strength of password
and allows the users to set only those passwords which are
secure enough. Would you like to setup VALIDATE PASSWORD component?
Press y|Y for Yes, any other key for No: y #是否更改密码
There are three levels of password validation policy: #更改密码安全等级
LOW Length >= 8
MEDIUM Length >= 8, numeric, mixed case, and special characters
STRONG Length >= 8, numeric, mixed case, special characters and dictionary file
Please enter 0 = LOW, 1 = MEDIUM and 2 = STRONG: 0
Please set the password for root here.
New password: #新密码
Re-enter new password: #验证新密码
Estimated strength of the password: 50
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : y #是否使用该密码
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production
environment.
Remove anonymous users? (Press y|Y for Yes, any other key for No) : y #是否去除匿名用户登录
Success.
Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.
Disallow root login remotely? (Press y|Y for Yes, any other key for No) : y #是否拒绝超级用户远程登录
Success.
By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production
environment.
Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y #是否测试库
- Dropping test database...
Success.
- Removing privileges on test database...
Success.
Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y #是否刷新数据库
Success.
All done!测试安装成功与否
[root@mysql ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 13
Server version: 8.0.36 Source distribution
Copyright (c) 2000, 2024, Oracle and/or its affiliates.
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>数据库的基础操作（sql语句的基本知识）
shell
#显示库名称
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
#创建数据库
mysql> CREATE DATABASES lsy;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DATABASES lsy' at line 1
mysql> CREATE DATABASE lsy;
Query OK, 1 row affected (0.01 sec)
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| lsy |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
#使用数据库
mysql> USE lsy;
Database changed
#显示库中的表
mysql> USE lsy;
Database changed
mysql> SHOW TABLES;
Empty set (0.00 sec)
#显示其他库中的表
#以MySQL为例子
mysql> SHOW TABLES FROM mysql;
+------------------------------------------------------+
| Tables_in_mysql |
+------------------------------------------------------+
| columns_priv |
| component |
| db |
| default_roles |
| engine_cost |
| func |
| general_log |
| global_grants |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| password_history |
| plugin |
| procs_priv |
| proxies_priv |
| replication_asynchronous_connection_failover |
| replication_asynchronous_connection_failover_managed |
| replication_group_configuration_version |
| replication_group_member_actions |
| role_edges |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+------------------------------------------------------+
37 rows in set (0.00 sec)
#在MySQL中建立表
mysql> CREATE TABLE mysql.userlist;
mysql> CREATE TABLE mysql.userlist ( username varchar(10) null , passwd varchar(50) not null );
#括号内依次为表头名称 字符长度 not null为非空
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES FROM mysql;
+------------------------------------------------------+
| Tables_in_mysql |
+------------------------------------------------------+
| columns_priv |
| component |
| db |
| default_roles |
| engine_cost |
| func |
| general_log |
| global_grants |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| password_history |
| plugin |
| procs_priv |
| proxies_priv |
| replication_asynchronous_connection_failover |
| replication_asynchronous_connection_failover_managed |
| replication_group_configuration_version |
| replication_group_member_actions |
| role_edges |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
| userlist |
+------------------------------------------------------+
38 rows in set (0.00 sec)
#删除数据库
mysql> DROP TABLE mysql.userlist ;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES FROM mysql;
+------------------------------------------------------+
| Tables_in_mysql |
+------------------------------------------------------+
| columns_priv |
| component |
| db |
| default_roles |
| engine_cost |
| func |
| general_log |
| global_grants |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| password_history |
| plugin |
| procs_priv |
| proxies_priv |
| replication_asynchronous_connection_failover |
| replication_asynchronous_connection_failover_managed |
| replication_group_configuration_version |
| replication_group_member_actions |
| role_edges |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+------------------------------------------------------+
37 rows in set (0.00 sec)
#建立当前库内表
mysql> CREATE TABLE userlist ( username varchar(10) null , passwd varchar(50) not null );
Query OK, 0 rows affected (0.02 sec)
mysql> SHOW TABLES;
+---------------+
| Tables_in_lsy |
+---------------+
| userlist |
+---------------+
1 row in set (0.00 sec)
#插入信息
mysql> INSERT INTO userlist VALUES ('user1','123');
Query OK, 1 row affected (0.00 sec)
#插入多条数据
mysql> INSERT INTO userlist VALUES ('user3','333'),('user2','222');
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
#查看所有数据
mysql> SELECT * FROM userlist;
+----------+--------+
| username | passwd |
+----------+--------+
| user1 | 123 |
+----------+--------+
1 row in set (0.00 sec)
#查询某列
mysql> SELECT username from userlist ;
+----------+
| username |
+----------+
| user1 |
| user3 |
| user2 |
+----------+
3 rows in set (0.00 sec)
#查询某列中某个固定的值多列可加and后面加条件
mysql> SELECT username from userlist WHERE passwd='333' ;
+----------+
| username |
+----------+
| user3 |
+----------+
1 row in set (0.01 sec)
#修改数据库名称
[root@mysql mysql]# cd /var/lib/mysql
[root@mysql mysql]# mv lsy/ lvsi
#！！！不建议修改数据库名称，会导致数据丢失！！！#
#修改表名称
mysql> SHOW TABLES;
+---------------+
| Tables_in_lsy |
+---------------+
| userlist |
+---------------+
1 row in set (0.00 sec)
mysql> ALTER TABLE userlist RENAME user_list;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES;
+---------------+
| Tables_in_lsy |
+---------------+
| user_list |
+---------------+
1 row in set (0.00 sec)
#增加一列
mysql> DESC user_list;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(10) | YES | | NULL | |
| passwd | varchar(50) | NO | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
mysql> ALTER TABLE user_list ADD age varchar(4) ;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC user_list;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(10) | YES | | NULL | |
| passwd | varchar(50) | NO | | NULL | |
| age | varchar(4) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
#删除列
mysql> ALTER TABLE user_list DROP age ;
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC user_list;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(10) | YES | | NULL | |
| passwd | varchar(50) | NO | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
#插入列到passwd前
mysql> ALTER TABLE user_list ADD age varchar(4) AFTER username;
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC user_list;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(10) | YES | | NULL | |
| age | varchar(4) | YES | | NULL | |
| passwd | varchar(50) | NO | | NULL | |
+----------+-------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
#更新某列数据
mysql> SELECT * FROM user_list;
+----------+------+--------+
| username | age | passwd |
+----------+------+--------+
| user1 | NULL | 123 |
| user3 | NULL | 333 |
| user2 | NULL | 222 |
+----------+------+--------+
3 rows in set (0.00 sec)
mysql> UPDATE user_list SET age='20';
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> SELECT * FROM user_list;
+----------+------+--------+
| username | age | passwd |
+----------+------+--------+
| user1 | 20 | 123 |
| user3 | 20 | 333 |
| user2 | 20 | 222 |
+----------+------+--------+
3 rows in set (0.00 sec)
#更新指定数据
mysql> UPDATE user_list SET age='15' WHERE username='user3';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM user_list;
+----------+------+--------+
| username | age | passwd |
+----------+------+--------+
| user1 | 20 | 123 |
| user3 | 15 | 333 |
| user2 | 20 | 222 |
+----------+------+--------+
3 rows in set (0.00 sec)
#备份数据库中所有数据到all.sql文件中
[root@mysql mysql]# mysqldump -uroot -p12345678 -A > /mnt/all.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
-- MySQL dump 10.13 Distrib 8.0.36, for Linux (x86_64)
[root@mysql mysql]# mysqldump -uroot -p12345678 -A |wc -l
mysqldump: [Warning] Using a password on the command line interface can be insecure.
1071
#备份数据库但不备份数据
[root@mysql mysql]# mysqldump -uroot -p12345678 -A --no-data > /mnt/all.sql
[root@mysql mysql]# mysqldump -uroot -p12345678 -A --no-data |wc -l
mysqldump: [Warning] Using a password on the command line interface can be insecure.
760
#备份指定的库
[root@mysql mysql]# mysqldump -uroot -p12345678 lsy > /mnt/lsy.sql
#删除表
mysql> DROP TABLE user_list;
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT * FROM user_list;
ERROR 1146 (42S02): Table 'lsy.user_list' doesn't exist
mysql>
#删除库
mysql> DROP DATABASE lsy;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW DATABASES ;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.01 sec)
#恢复数据库
[root@mysql mysql]# mysql -uroot -p12345678 -e "SHOW DATABASES"
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
[root@mysql mysql]# mysql -uroot -p12345678 < /mnt/lsy.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1046 (3D000) at line 22: No database selected
#创建表
[root@mysql mysql]# mysql -uroot -p12345678 -e "CREATE DATABASE lsy"
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@mysql mysql]# mysql -uroot -p12345678 -e "SHOW DATABASES"
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| lsy |
| mysql |
| performance_schema |
| sys |
+--------------------+
#恢复备份
[root@mysql mysql]# mysql -uroot -p12345678 lsy < /mnt/lsy.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@mysql mysql]# mysql -uroot -p12345678 -e "SHOW DATABASES"
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database |
+--------------------+
| information_schema |
| lsy |
| mysql |
| performance_schema |
| sys |
+--------------------+
#！！！注意本文在实验环境中进行为高效实验故裸露数据库密码，生产环境中不可裸露密码！！！#
#应该使用
[root@mysql mysql]# mysql -uroot -p ......