:存储在硬盘
:存储在内存,变量的形式key=value
:数据是存放在“文件(数据文件)”中
数据结构模型主要有:
关系模型:
二维关系:row,column
数据库管理系统:DBMS
关系:Relational,RDBMS
常见的关系型数据库管理系统:
约束:constraint,向数据表提供的数据要遵守的限制
索引:将表中的一个或多个字段中的数据复制一份另存,并且这些数据需要按特定次序排序存储
关系型数据库的常见组件有:
SQL语句有三种类型:
|SQL语句类型 |对应操作|
|--- |: -----|
|DDL |CREATE:创建; DROP:删除;ALTER:修改;|
|DML |INSERT:向表中插入数据;DELETE:删除表中数据;UPDATE:更新表中数据;SELECT:查询表中数据;|
|DCL |GRANT:授权;REVOKE:移除授权;|
mysql安装方式有三种:
配置mysql的yum源
1.下载mysql的yum repository
[root@localhost ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm
2.更新下载好的yum repository
[root@localhost ~]# rpm -Uvh mysql57-community-release-el7-11.noarch.rpm
3.查看/etc/yum.repos.d/下多了两个mysql的repo
[root@localhost ~]# ls /etc/yum.repos.d/ myrepo.repo mysql-community.repo mysql-community-source.repo
4.开始安装mysql,安装前先禁用默认的mysql模块
[root@localhost ~]# yum module disable mysql [root@localhost ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel --nogpgcheck
启动mysql并设置开机自动启动
[root@localhost ~]# systemctl enable --now mysqld
查看3306端口已经监听
[root@localhost ~]# systemctl status mysqld ● mysqld.service - MySQL Server Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled) Active: active (running) since Sun 2022-07-24 13:57:18 CST; 3min 9s ago Docs: man:mysqld(8) http://dev.mysql.com/doc/refman/en/using-systemd.html Process: 2729 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS) Process: 2679 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS) Main PID: 2731 (mysqld) Tasks: 27 (limit: 11201) Memory: 316.4M CGroup: /system.slice/mysqld.service └─2731 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid Jul 24 13:57:14 localhost.localdomain systemd[1]: Starting MySQL Server... Jul 24 13:57:18 localhost.localdomain systemd[1]: Started MySQL Server. [root@localhost ~]# ss -antl State Recv-Q Send-Q Local Address:Port Peer Address:Port Process LISTEN 0 128 0.0.0.0:22 0.0.0.0:* LISTEN 0 80 *:3306 *:* LISTEN 0 128 [::]:22 [::]:*
在日志文件中找出临时密码
[root@localhost ~]# grep "password" /var/log/mysqld.log 2022-07-24T05:57:15.560498Z 1 [Note] A temporary password is generated for root@localhost: g>u%=yugt6gW
使用获取到的临时密码登录mysql,密码为 g>u%=yugt6gW
[root@localhost ~]# mysql -uroot -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) [root@localhost ~]# mysql -uroot -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 Server version: 5.7.38 Copyright (c) 2000, 2022, 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>
修改mysql登录密码
mysql> alter user 'root'@'localhost' identified by 'Luojialong123!'; Query OK, 0 rows affected (0.00 sec)
使用新密码登录mysql
[root@localhost ~]# mysql -uroot -pLuojialong123! mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 4 Server version: 5.7.38 MySQL Community Server (GPL) Copyright (c) 2000, 2022, 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>
避免mysql自动升级,卸载最开始安装的yum源
[root@localhost ~]# rpm -e mysql57-community-release
[root@localhost ~]# yum -y install mariadb* [root@localhost ~]# systemctl enable --now mariadb [root@localhost ~]# systemctl status mariadb ● mariadb.service - MariaDB 10.3 database server Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: d> Active: active (running) since Sun 2022-07-24 02:21:37 EDT; 19s ago Docs: man:mysqld(8) https://mariadb.com/kb/en/library/systemd/ Process: 7967 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, status=0> Process: 7831 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mariadb.service (code=> Process: 7806 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/S> Main PID: 7936 (mysqld) Status: "Taking your SQL requests now..." Tasks: 30 (limit: 4615) Memory: 103.9M CGroup: /system.slice/mariadb.service └─7936 /usr/libexec/mysqld --basedir=/usr
设置密码
[root@localhost ~]# mysql Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 8 Server version: 10.3.28-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> set password = password('123456'); Query OK, 0 rows affected (0.000 sec) MariaDB [(none)]> \q Bye
测试登录
[root@localhost ~]# mysql -uroot -p123456 Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 9 Server version: 10.3.28-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]>