mysql基础

Posted 2021-03-02

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1.关系型数据库介绍

1.1数据库结构模型

1.2RDBMS专业名词


1.3关系型数据库的常见组件

1.4SQL语句



2.mysql安装与配置
2.1mysql 安装



2.2mysql配置

[root@localhost ~]# systemctl start mysqld
[root@localhost ~]# systemctl status myaqld
Unit myaqld.service could not be found.
[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 六 2020-04-04 14:44:49 CST; 2min 37s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 6677 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 6628 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 6681 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─6681 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

4月 04 14:43:52 localhost.localdomain systemd[1]: Starting MySQL Server...
4月 04 14:44:49 localhost.localdomain systemd[1]: Started MySQL Server.

[root@localhost ~]# ss -antl
State       Recv-Q Send-Q        Local Address:Port                       Peer Address:Port              
LISTEN      0      128                       *:111                                   *:*                  
LISTEN      0      128                       *:22                                    *:*                  
LISTEN      0      100               127.0.0.1:25                                    *:*                  
LISTEN      0      128                      :::111                                  :::*                  
LISTEN      0      32                       :::21                                   :::*                  
LISTEN      0      128                      :::22                                   :::*                  
LISTEN      0      100                     ::1:25                                   :::*                  
LISTEN      0      80                       :::3306                                 :::*                  
[root@localhost ~]# grep "password" /var/log/mysqld.log
2020-04-04T06:44:15.530430Z 1 [Note] A temporary password is generated for root@localhost: &bjGrVMxL5Dj

//此处的临时密码为：&bjGrVMxL5Dj
//每个人的临时密码都不同；

使用获取到的临时密码登录mysql
[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 6
Server version: 5.7.29

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

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.
//修改mysql登录密码
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)

mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)

mysql>  ALTER USER ‘root‘@‘localhost‘ IDENTIFIED BY ‘whb123!‘;
Query OK, 0 rows affected (0.78 sec)

mysql> quit
Bye

//为避免mysql自动升级，这里需要卸载最开始安装的yum源
[root@localhost ~]# rpm -qa|grep mysql
mysql57-community-release-el7-10.noarch
mysql-community-client-5.7.29-1.el7.x86_64
mysql-community-libs-5.7.29-1.el7.x86_64
mysql-community-server-5.7.29-1.el7.x86_64
mysql-community-libs-compat-5.7.29-1.el7.x86_64
mysql-community-common-5.7.29-1.el7.x86_64
mysql-community-devel-5.7.29-1.el7.x86_64
[root@localhost ~]# yum -y remove mysql57-community-release-el7-10.noarch

3.mysql的程序组成

3.1mysql工具使用

[root@localhost ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.29, for Linux (x86_64) using  EditLine wrapper
[root@localhost ~]# mysql -uroot -pwhb123! -h127.0.0.1
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 7
Server version: 5.7.29 MySQL Community Server (GPL)

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

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> quit
Bye
[root@localhost ~]# mysql -uroot -p -h 127.0.0.1 -e ‘SHOW DATABASES;‘
Enter password: 
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

进入数据库创建lol这个数据库，对它进行创建和删除
[root@localhost ~]# mysql -uroot -pwhb123! -h127.0.0.1
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 10
Server version: 5.7.29 MySQL Community Server (GPL)

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

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> CREATE DATABASE IF NOT EXISTS lol;
Query OK, 1 row affected (0.09 sec)

mysql> SHOW DATABASES
    -> SHOW DATABASES;
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 ‘SHOW DATABASES‘ at line 2
mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| lol                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.05 sec)

mysql> DROP DATABASE IF EXISTS lol;
Query OK, 0 rows affected (0.44 sec)

mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

进入lol数据库里创建abc这个表，表的字段有id，name，age
mysql> use lol;
Database changed
mysql> CREATE TABLE abc (id int NOT NULL,name VARCHAR(100) NOT NULL,age tinyint);
Query OK, 0 rows affected (1.77 sec)

mysql> SHOW TABLES;
+---------------+
| Tables_in_lol |
+---------------+
| abc           |
+---------------+
1 row in set (0.00 sec)

查看abc这个表的结构
mysql> DESC lol.abc;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(11)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.55 sec)

对abc这个表做删除操作
mysql> use lol;
Database changed
mysql> DROP TABLE abc;
Query OK, 0 rows affected (0.50 sec)

mysql> SHOW TABLES;
Empty set (0.00 sec)