Django web开发(二) - Mysql数据库

mysql数据库

Mysql的安装(CentOS7)

以Mysql5.7.31版本为例

下载

这里为了方便演示,使用yum进行下载(其他系统的请使用自己对应的安装命令,在Windows或者MacOS上安装,请去官网下载二进制安装包),不进行源码编译安装

cat > /etc/yum.repos.d/mysql57.repo <<EOF
[mysql-5.7-***munity]
name=MySQL 5.7 ***munity Server
baseurl=https://mirrors.tuna.tsinghua.edu.***/mysql/yum/mysql-5.7-***munity-el7-x86_64/
enabled=1
gpgcheck=1
gpgkey=https://repo.mysql.***/RPM-GPG-KEY-mysql
EOF


rpm --import https://repo.mysql.***/RPM-GPG-KEY-mysql-2022  
yum -y install mysql-server 

# 启动mysql
systemctl start mysqld
# 查看默认密码
cat /var/log/mysqld.log | grep password

# 登录Mysql
mysql -uroot -pwIu8_wS_nXpf

# 修改密码
mysql> set password=password('Syz123!@#');

# 如果日志内容报错[ERROR]
/usr/bin/mysql_upgrade -u root -p --force
Enter password:             ### 设定密码

修改配置文件

修改Mysql的数据存储目录datadir

[mysqld]
datadir=/usr/local/mysql/data
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is re***mended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

创建目录并重启Mysql服务

mkdir -p /usr/local/mysql/data
systemctl restart mysql

[root@hecs-33592 ~]# ll /usr/local/mysql/data
total 122940
-rw-r----- 1 mysql mysql       56 Dec  9 13:45 auto.***f
-rw------- 1 mysql mysql     1676 Dec  9 13:45 ca-key.pem
-rw-r--r-- 1 mysql mysql     1112 Dec  9 13:45 ca.pem
-rw-r--r-- 1 mysql mysql     1112 Dec  9 13:45 client-cert.pem
-rw------- 1 mysql mysql     1680 Dec  9 13:45 client-key.pem
-rw-r----- 1 mysql mysql      436 Dec  9 13:45 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Dec  9 13:46 ibdata1
-rw-r----- 1 mysql mysql 50331648 Dec  9 13:46 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Dec  9 13:45 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Dec  9 13:46 ibtmp1
drwxr-x--- 2 mysql mysql     4096 Dec  9 13:45 mysql
drwxr-x--- 2 mysql mysql     4096 Dec  9 13:45 performance_schema
-rw------- 1 mysql mysql     1680 Dec  9 13:45 private_key.pem
-rw-r--r-- 1 mysql mysql      452 Dec  9 13:45 public_key.pem
-rw-r--r-- 1 mysql mysql     1112 Dec  9 13:45 server-cert.pem
-rw------- 1 mysql mysql     1680 Dec  9 13:45 server-key.pem
drwxr-x--- 2 mysql mysql    12288 Dec  9 13:45 sys

Mysql强制重置密码

[root@hecs-33592 ~]# vim /etc/my.***f
skip-grant-tables	# 最下面加入这一行

[root@hecs-33592 ~]# systemctl restart mysqld

[root@hecs-33592 ~]# mysql -uroot -p
Enter password:		# 直接回车 

mysql> use mysql;
Reading table information for ***pletion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> update user set authentication_string=password('Syz123!@#') where user='root';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

然后注释掉/etc/my.***f中的skip-grant-tables
重启mysql

mysql> create database d1 DEFAULT CHARSET utf8 COLLATE utf8_general_ci;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

# 需要重新修改密码
mysql> set password=password('Syz123!@#');
Query OK, 0 rows affected, 1 warning (0.00 sec)

远程可登录

如果要配置Mysql为远程可登录,可作如下操作:

host改为自己的网段

mysql> use mysql
mysql> update user set host='192.168.10.%' where user='root';
mysql> flush privileges;

数据库管理

• 创建数据库

create database 数据库名字 DEFAULT CHARSET utf8 COLLATE utf8_general_ci;

Example

create database d1 DEFAULT CHARSET utf8 COLLATE utf8_general_ci;

• 删除数据库

drop database 数据库名字;

数据表的管理

• 进入数据库

use 数据库名称;

• 查看所有数据表

show tables;

• 创建表

create table 表名称(
	列名称 类型,
	列名称 类型,
	列名称 类型
) default charset=utf8;

Example:

create table tb1(
	id int,
	name varchar(16) not null,	--不允许为空
	age int	null				--允许为空
) default charset=utf8;

create table tb1(
	id int,
	name varchar(16),
	age int default 3			--插入数据时,age列的默认值为3
) default charset=utf8;

create table tb1(
	id int primary key,			--主键(不允许为空,不允许重复)
	name varchar(16),
	age int
) default charset=utf8;

create table tb1(
	id int auto_increment primary key,		--内部维护,自增
	name varchar(16),
	age int
) default charset=utf8;

一般情况下,我们都会这样写:

create table tb1(
	id int not null auto_increment primary key,
	name varchar(16),
	age int
) default charset=utf8; 

• 删除表

drop table 表名称;

查看表结构

mysql> desc tb1;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(16) | YES  |     | NULL    |                |
| age   | int(11)     | YES  |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+

常用数据类型

• tinyint

有符号, 取值范围: -128 ~ 127(有正有负)
无符号, 取值范围: 0 ~ 255(只有正)

create table tb1(
	id int not null auto_increment primary key,
	age tinyint				--有符号, 取值范围: -128 ~ 127
) default charset=utf8;

create table tb1(
	id int not null auto_increment primary key,
	age tinyint unsigned	--无符号, 取值范围: 0 ~ 255
) default charset=utf8;

• int

有符号, 取值范围: -2147483648 ~ 2147483647(有正有负)
无符号, 取值范围: 0 ~ 4294967295(只有正)

• bigint

有符号, 取值范围: -9223372036854775808 ~ 9223372036854775807(有正有负)
无符号, 取值范围: 0 ~ 18446744073709551615(只有正)

• float
• double
• decimal

create table tb1(
	id int auto_increment primary key,		--内部维护,自增
	name varchar(16),
	salary decimal(8,2)						--一共8位(整数位数+小数点位数), 保留小数点后2位
) default charset=utf8;

• char

定长字符串, 默认固定用 11 个字符串进行存储,哪怕字符串个数不足,也按照11个字符存储
最多能存储255个字节的数据
查询效率高

• varchar

变长字符串,默认最长 11 个字符,真实数据多长就按多长存储
最多能存储 65535 个字节的数据,中文可存储 65535/3 个汉字
相对 char 类型,查询效率低

• text

保存变长的大字符串,可以最多到 65535 个字符
一般用于文章和新闻

• mediumtext
• longtext
• datetime

YYYY-MM-DD HH:MM:SS (1000-01-01 00:00:00/9999-12-31 23:59:59)

• date

YYYY-MM-DD (1000-01-01/9999-12-31)

数据管理

添加数据

• 插入数据

insert into 表名称(字段1, 字段2, ...) values(1, "张三", ...);

Example:

insert into tb1(name,age) values("张三",25);

查询数据

select 字段名(或者*) from 表名称;
select 字段名(或者*) from 表名称 where 条件;

Example:

mysql> select * from tb1;
+----+--------+------+
| id | name   | age  |
+----+--------+------+
|  1 | 张三   |   25 |
+----+--------+------+

mysql> select name from tb1;
+--------+
| name   |
+--------+
| 张三   |
+--------+

mysql> select * from tb1 where id = 1;
+----+--------+------+
| id | name   | age  |
+----+--------+------+
|  1 | 张三   |   25 |
+----+--------+------+

删除数据

delete from 表名称;				--删除所有数据
delete from 表名称 where 条件;	--删除指定数据

Example:

delete from tb1 where id = 1;
delete from tb1 where id = 1 and name = "张三";
delete from tb1 where id = 1 or id = 100;
delete from tb1 where id > 100;
delete from tb1 where id != 50;
delete from tb1 where id in (10,15);

修改数据

update 表名称 set 列 = 值;				--修改一列
update 表名称 set 列 = 值, 列 = 值;		--修改多列
update 表名称 set 列 = 值 where 条件;		--修改某行某列

Example:

update tb1 set name="李四" where id = 1;
update tb1 set age=age+10 where name=""李四;

员工管理

命令实现

使用Mysql内置工具(命令)

• 创建数据库: uni***
• 创建数据表: admin
  • 表名称: admin
  • 列:
    • id 整型 自增 主键
    • username: 字符串 不为空
    • password: 字符串 不为空
    • mobile: 字符串 不为空

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| d1                 |
| mysql              |
| performance_schema |
| sys                |
| uni***             |
+--------------------+
6 rows in set (0.00 sec)

mysql> use uni***
Database changed
mysql> create table admin (
    -> id int auto_increment primary key,
    -> username varchar(30) not null,
    -> password varchar(30) not null,
    -> mobile varchar(20) not null) default charset=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> desc admin;
+----------+-------------+------+-----+---------+----------------+
| Field    | Type        | Null | Key | Default | Extra          |
+----------+-------------+------+-----+---------+----------------+
| id       | int(11)     | NO   | PRI | NULL    | auto_increment |
| username | varchar(30) | NO   |     | NULL    |                |
| password | varchar(30) | NO   |     | NULL    |                |
| mobile   | varchar(20) | NO   |     | NULL    |                |
+----------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

Python管理数据库

添加数据

代码实现

Python 代码实现:

• 添加用户
• 删除用户
• 查看用户
• 更新用户信息

安装pymysql包

pip3 install pymysql

编辑python文件

#!/usr/bin/env python3

import pymysql

# 1.连接Mysql
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='Syz123!@#', charset='utf8', db='uni***')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 2.发送指令
cursor.execute("insert into admin(username, password, mobile) values('poker', '123456', '12345678912');")
conn.***mit()

# 3.关闭
cursor.close()
conn.close()

运行

/bin/python3 /root/python/Mysql/createData.py

验证

mysql> select * from admin;
+----+----------+----------+-------------+
| id | username | password | mobile      |
+----+----------+----------+-------------+
|  3 | poker    | 123456   | 12345678912 |
+----+----------+----------+-------------+
1 row in set (0.00 sec)

优化

#!/usr/bin/env python3

import pymysql

# 1.连接Mysql
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='Syz123!@#', charset='utf8', db='uni***')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 2.发送指令
sql = "insert into admin(username, password, mobile) values(%s, %s, %s);"
cursor.execute(sql, ['toker', '123456', '12355674325'])
conn.***mit()

# 3.关闭
cursor.close()
conn.close()

注意: sql语句不要使用字符串格式化,有会SQL注入的风险,需要使用 cursor.execute(sql, [参数1, 参数2, …])

查询数据

#!/usr/bin/env python3

import pymysql

# 1.连接Mysql
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                       passwd='Syz123!@#', charset='utf8', db='uni***')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 2.发送指令
sql = "select * from admin where id > %s"
cursor.execute(sql, [2, ])
# data_list = cursor.fetchall()		查询一条数据,为字典
data_list = cursor.fetchall()		# 查询所有符合条件的数据,为列表套多个
字典
for row_dict in data_list:
    print(row_dict)

# 3.关闭
cursor.close()
conn.close()

输出结果如下

[root@hecs-33592 ~]# /bin/python3 /root/python/Mysql/searchData.py 
{'id': 3, 'username': 'poker', 'password': '123456', 'mobile': '12345678912'}
{'id': 4, 'username': 'toker', 'password': '123456', 'mobile': '12355674325'}

删除数据

删除 id 大于 3 的行

#!/usr/bin/env python3

import pymysql

# 1.连接Mysql
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                       passwd='Syz123!@#', charset='utf8', db='uni***')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 2.发送指令
sql = "delete from admin where id > %s"
cursor.execute(sql, [3, ])
conn.***mit()

# 3.关闭
cursor.close()
conn.close()

修改数据

#!/usr/bin/env python3

import pymysql

# 1.连接Mysql
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                       passwd='Syz123!@#', charset='utf8', db='uni***')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

# 2.发送指令
sql = "update admin set mobile=%s where id = %s"
cursor.execute(sql, ['12332145665', 3])
conn.***mit()

# 3.关闭
cursor.close()
conn.close()

案例: Flask + Mysql

main.py

from flask import Flask, render_template, request
import pymysql

app = Flask(__name__)


@app.route("/add/user", methods=['GET', 'POST'])
def addUser():
    if request.method == 'GET':
        return render_template("addUser.html")
    else:
        username = request.form.get('user')
        password = request.form.get('pwd')
        mobile = request.form.get('mobile')

        # 1.连接Mysql
        conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                            passwd='Syz123!@#', charset='utf8', db='uni***')
        cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

        # 2.发送指令
        sql = "insert into admin(username, password, mobile) values(%s, %s, %s);"
        cursor.execute(sql, [username, password, mobile])
        conn.***mit()

        # 3.关闭
        cursor.close()
        conn.close()

        return "添加成功"


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5200, debug=True)

编写一个简单的前端页面添加数据

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <h1>添加用户</h1>
    <form method="post" action="/add/user">
        <input type="text" name="user" placeholder="用户名">
        <input type="text" name="pwd" placeholder="密码">
        <input type="text" name="mobile" placeholder="手机号">
        <input type="submit" value="提 交">
    </form>
</body>
</html>

mysql> select * from admin;
+----+----------+----------+-------------+
| id | username | password | mobile      |
+----+----------+----------+-------------+
|  3 | poker    | 123456   | 12332145665 |
|  5 | roker    | 123456   | 4563112345  |
+----+----------+----------+-------------+

案例: 查询所有用户

main.py

from flask import Flask, render_template, request
import pymysql

app = Flask(__name__)


@app.route("/add/user", methods=['GET', 'POST'])
def addUser():
    if request.method == 'GET':
        return render_template("addUser.html")
    else:
        username = request.form.get('user')
        password = request.form.get('pwd')
        mobile = request.form.get('mobile')

        # 1.连接Mysql
        conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                            passwd='Syz123!@#', charset='utf8', db='uni***')
        cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

        # 2.发送指令
        sql = "insert into admin(username, password, mobile) values(%s, %s, %s);"
        cursor.execute(sql, [username, password, mobile])
        conn.***mit()

        # 3.关闭
        cursor.close()
        conn.close()

        return "添加成功"


@app.route("/show/user", methods=['GET', 'POST'])
def showUser():
    username = request.form.get('user')
    password = request.form.get('pwd')
    mobile = request.form.get('mobile')

    # 1.连接Mysql
    conn = pymysql.connect(host='127.0.0.1', port=3306, user='root',
                        passwd='Syz123!@#', charset='utf8', db='uni***')
    cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

    # 2.发送指令
    sql = "select * from admin"
    cursor.execute(sql)
    data_list = cursor.fetchall()

    # 3.关闭
    cursor.close()
    conn.close()

    return render_template("showUser.html", data_list=data_list)


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5200, debug=True)

编写HTML文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <h1>用户列表</h1>
    <table border="1">
        <thead>
            <tr>
                <th>ID</th>
                <th>姓名</th>
                <th>密码</th>
                <th>手机号</th>
            </tr>
        </thead>
        <tbody>
            {% for item in data_list %}
            <tr>
                <td>{{ item.id }}</td>
                <td>{{ item.username }}</td>
                <td>{{ item.password }}</td>
                <td>{{ item.mobile }}</td>
            </tr>
            {% endfor %}
        </tbody>
    </table>
</body>
</html>

优化

加入 bootstrap.css

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>

    <link rel="stylesheet" href="../static/plugins/bootstrap-3.4.1/css/bootstrap.css">

</head>
<body>
    <div class="container">
        <h1>用户列表</h1>
        <table class="table table-bordered">
            <thead>
                <tr>
                    <th>ID</th>
                    <th>姓名</th>
                    <th>密码</th>
                    <th>手机号</th>
                </tr>
            </thead>
            <tbody>
                {% for item in data_list %}
                <tr>
                    <td>{{ item.id }}</td>
                    <td>{{ item.username }}</td>
                    <td>{{ item.password }}</td>
                    <td>{{ item.mobile }}</td>
                </tr>
                {% endfor %}
            </tbody>
        </table>
    </div>
    
</body>
</html>