1、创建一个示例数据库
#创建数据库
mysql> create DATABASE django;
Query OK, 1 row affected (0.11 sec)
#选择数据库
mysql> use django;
Database changed
#创建数据表
mysql> create TABLE django_tbl(
-> age INT);
Query OK, 0 rows affected (0.21 sec)
#插入数据
mysql> insert into django_tbl (age) VALUES (12);
Query OK, 1 row affected (0.10 sec)
mysql> select* from django_tbl;
+------+
| age |
+------+
| 12 |
+------+
1 row in set (0.00 sec)2、安装pymysql
pip install pymysql3、在工程下的__init__.py导入库
import pymysql
pymysql.install_as_MySQLdb()
4、在settings.py中设置mysql的链接信息
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'django',
'USER': 'root',
'PASSWORD': 'lmx082902*',
'HOST': 'localhost',
'PORT': '3306',
}
}
5、连接mysql创建对应数据库
#管理员身份允许cmd
C:\Users\Administrator>mysql -u root -p
Enter password: **********
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 8.0.12 MySQL Community Server - GPL
Copyright (c) 2000, 2018, 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 bbs;
Query OK, 1 row affected (0.07 sec)
6、修改应用下models.py
# Create your models here.
"""
创建学生信息表模型
"""
from django.db import models
"""
该类是用来生成数据库的 必须要继承models.Model
"""
class Student(models.Model):
"""
创建如下几个表的字段
"""
# 学号 primary_key=True: 该字段为主键
studentNum = models.CharField('学号', primary_key=True, max_length=15)
# 姓名 字符串 最大长度20
name = models.CharField('姓名', max_length=20)
# 年龄 整数 null=False, 表示该字段不能为空
age = models.IntegerField('年龄', null=False)
# 性别 布尔类型 默认True: 男生 False:女生
sex = models.BooleanField('性别', default=True)
# 手机 unique=True 该字段唯一
mobile = models.CharField('手机', unique=True, max_length=15)
# 创建时间 auto_now_add：只有在新增的时候才会生效
createTime = models.DateTimeField(auto_now_add=True)
# 修改时间 auto_now： 添加和修改都会改变时间
modifyTime = models.DateTimeField(auto_now=True)
# 指定表名 不指定默认APP名字——类名(app_demo_Student)
class Meta:
db_table = 'student'
"""
学生社团信息表
"""
class studentUnion(models.Model):
# 自增主键, 这里不能设置default属性，负责执行save的时候就不会新增而是修改元素
id = models.IntegerField(primary_key=True)
# 社团名称
unionName = models.CharField('社团名称', max_length=20)
# 社团人数
unionNum = models.IntegerField('人数', default=0)
# 社团负责人 关联Student的主键 即studentNum学号 一对一的关系,on__delete 属性在django2.0之后为必填属性后面会介绍
unionRoot = models.OneToOneField(Student, on_delete=None)
class Meta:
db_table = 'student_union'
"""
OneToOneField： 一对一
ForeignKey: 一对多
ManyToManyField： 多对多(没有ondelete 属性)
"""7、执行迁移
#在数据库中创建了admin、auth等应用所需要的数据表
python manage.py migrate
mysql> show tables;
+----------------------------+
| Tables_in_bbs |
+----------------------------+
| auth_group |
| auth_group_permissions |
| auth_permission |
| auth_user |
| auth_user_groups |
| auth_user_user_permissions |
| django_admin_log |
| django_content_type |
| django_migrations |
| django_session |
+----------------------------+
10 rows in set (0.00 sec)
mysql>迁移过程中出现以下错误说明没有该数据库，需要创建数据库
self.connect()
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\connections.py", line 633, in connect
self._request_authentication()
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\connections.py", line 932, in _request_authentication
auth_packet = _auth.caching_sha2_password_auth(self, auth_packet)
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\_auth.py", line 239, in caching_sha2_password_auth
pkt = conn._read_packet()
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\connections.py", line 725, in _read_packet
packet.raise_for_error()
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\protocol.py", line 221, in raise_for_error
err.raise_mysql_exception(self._data)
File "D:\Program(X86_64)\Python\lib\site-packages\pymysql\err.py", line 143, in raise_mysql_exception
raise errorclass(errno, errval)
django.db.utils.OperationalError: (1049, "Unknown database 'django'")mysql> \d
ERROR:
DELIMITER must be followed by a 'delimiter' character or string
mysql> create database django;
Query OK, 1 row affected (0.10 sec)
mysql>
8、迁移文件
makemigrations会检测应用目录下是否存在migrations目录，如果没有则进行创建。会根据应用的结构定义生成一个0001_initial.py文件，执行migrate命令就可以创建数据表了。
每一次表结构的定义修改，都需要再次执行makemigrations命令，会重新生成一个新的数据库迁移文件，记录表结构之间的差异，执行migrate命令时会让新的迁移文件生效。
django会把每一次数据迁移记录到django_migrations表中，每一次 执行migrate前都会比较迁移文件是否已经记录在表中了，只有没出现过的才会执行。
python manage.py makemigrations
mysql> select * from django_migrations;
+----+--------------+------------------------------------------+----------------------------+
| id | app | name | applied |
+----+--------------+------------------------------------------+----------------------------+
| 1 | contenttypes | 0001_initial | 2021-05-05 06:56:32.461434 |
| 2 | auth | 0001_initial | 2021-05-05 06:56:35.427440 |
| 3 | admin | 0001_initial | 2021-05-05 06:56:36.325694 |
| 4 | admin | 0002_logentry_remove_auto_add | 2021-05-05 06:56:36.347685 |
| 5 | admin | 0003_logentry_add_action_flag_choices | 2021-05-05 06:56:36.367672 |
| 6 | contenttypes | 0002_remove_content_type_name | 2021-05-05 06:56:36.804290 |
| 7 | auth | 0002_alter_permission_name_max_length | 2021-05-05 06:56:37.115109 |
| 8 | auth | 0003_alter_user_email_max_length | 2021-05-05 06:56:37.175444 |
| 9 | auth | 0004_alter_user_username_opts | 2021-05-05 06:56:37.233449 |
| 10 | auth | 0005_alter_user_last_login_null | 2021-05-05 06:56:37.461381 |
| 11 | auth | 0006_require_contenttypes_0002 | 2021-05-05 06:56:37.479370 |
| 12 | auth | 0007_alter_validators_add_error_messages | 2021-05-05 06:56:37.498358 |
| 13 | auth | 0008_alter_user_username_max_length | 2021-05-05 06:56:37.740620 |
| 14 | auth | 0009_alter_user_last_name_max_length | 2021-05-05 06:56:38.276865 |
| 15 | auth | 0010_alter_group_name_max_length | 2021-05-05 06:56:38.333087 |
| 16 | auth | 0011_update_proxy_permissions | 2021-05-05 06:56:38.357071 |
| 17 | auth | 0012_alter_user_first_name_max_length | 2021-05-05 06:56:38.671544 |
| 18 | sessions | 0001_initial | 2021-05-05 06:56:38.840235 |
+----+--------------+------------------------------------------+----------------------------+
18 rows in set (0.00 sec)
mysql>