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django第六课 模型第一讲

时间:2019-02-23 00:27:53      阅读:248      评论:0      收藏:0      [点我收藏+]

1.数据库连接配置:

  django 连接mysql的配置流程:
    - 安装 pymysql pip install pymysql
  - 创建数据库用户
    有创建数据库权限的用户
  - 创建数据库
    

create database crm

 

- 修改配置
settins

 1 DATABASES = {
 2     default: {
 3         ENGINE: django.db.backends.mysql,
 4         NAME: crm,
 5         USER:root,
 6         PASSWORD:‘‘,
 7         HOST:101.132.193.205,
 8         PORT:3306
 9     }
10 }

 


- 修改项目文件夹(和settings.py文件所在的目录)下
__init__.py 文件
写上:

1 import pymysql
2 pymysql.install_as_MySQLdb()


- 设置时区 TIME_ZONE = ‘Asia/ShangHai‘ # 北京时间

 

2.django的ORM系统

-对象关系映射(Object Relational Mapping,简称ORM)! 简单的说就是用面向对象的方式,描述数据库,操作数据库,
达到不用编写SQL语句就能对数据库进行增删改查。

3.模型的创建与激活创建模型

Student的模型,代表啊学生 总结:
1. 每一个模型都是django.db.models.Model的子类
2. 类变量 表示模型中的数据库字段
3. 每一个字段由一个字段类的实例表示
激活模型
1.在项目中注册app
2.运行数据库迁移命令(一定要在项目根目录下)

python mange.py makemigrations teacher

 

告诉django,我们做了哪些数据库的更改
迁移
sqlmigrate 从迁移获取sql语句

1 (django) [root@iZuf68mx592121gk7l1ca1Z crm]# python3 manage.py sqlmigrate teacher 0001
2 BEGIN;
3 --
4 -- Create model Student
5 --
6 CREATE TABLE `teacher_student` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `name` varchar(20) NOT NULL, `age` smallint NOT NULL, `sex` smallint NOT NULL, `qq` varchar(20) NOT NULL, `phone` varchar(20) NOT NULL, `c_time` datetime(6) NOT NULL);
7 COMMIT;

 


3.运行migrate命令,使迁移生效

python manage.py migrate teacher

 

# 表名 appname_模型name.lower

4.数据的增删改查

  增:

  第一种方法:

    

In [10]: s1                                                                                                
Out[10]: <Student: Student object (None)>

In [11]: s1 = Student(name = donghao,age=25,qq = 11111)                                                

In [12]: s1.save()                                                                                         

In [13]: Student.objects.all()                                                                             
Out[13]: <QuerySet [<Student: Student object (1)>]>

第二种方法:

  

 1 In [14]: s2 = Student()                                                                                    
 2 
 3 In [15]: s2.name = xinlan                                                                                
 4 
 5 In [16]: s2.age = 30                                                                                       
 6 
 7 In [17]: s2.save()                                                                                         
 8 
 9 In [18]: Student.objects.all()                                                                             
10 Out[18]: <QuerySet [<Student: Student object (1)>, <Student: Student object (2)>]>

 

mysql> select * from teacher_student
    -> ;
+----+---------+-----+-----+-------+-------+----------------------------+
| id | name    | age | sex | qq    | phone | c_time                     |
+----+---------+-----+-----+-------+-------+----------------------------+
|  1 | donghao |  25 |   1 | 11111 |       | 2019-02-22 15:17:07.621733 |
|  2 | xinlan  |  30 |   1 |       |       | 2019-02-22 15:19:38.728134 |
+----+---------+-----+-----+-------+-------+----------------------------+
2 rows in set (0.00 sec)

第三种方法:

  

In [7]: Student.objects.create(name=weigang,age=22)                                                      
Out[7]: <Student: weigang-22

第四种方法:

In [8]: Student.objects.all()                                                                              
Out[8]: <QuerySet [<Student: donghao-25>, <Student: xinlan-30>, <Student: weigang-22>]>

In [9]: s = Student.objects.get_or_create(name = moran)                                                  

In [10]: s                                                                                                 
Out[10]: (<Student: moran-0>, True)

In [11]: s = Student.objects.get_or_create(name = donghao)                                               

In [12]: s                                                                                                 
Out[12]: (<Student: donghao-25>, False)

  返回的是一个元祖
  false 代码查询到的
  true 代表创建的

 

查询:

  查询所有的

  

In [13]: Student.objects.all()                                                                             
Out[13]: <QuerySet [<Student: donghao-25>, <Student: xinlan-30>, <Student: weigang-22>, <Student: moran-0>]>

  调用的sql语句

  

In [15]: print(res.query)                                                                                  
SELECT `teacher_student`.`id`, `teacher_student`.`name`, `teacher_student`.`age`, `teacher_student`.`sex`, `teacher_student`.`qq`, `teacher_student`.`phone`, `teacher_student`.`c_time` FROM `teacher_student`

查询一条数据:

  

In [16]: Student.objects.get(id=1)                                                                         
Out[16]: <Student: donghao-25>
In [17]: Student.objects.get(pk=1)                                                                         
Out[17]: <Student: donghao-25>

查询多条数据

In [18]: res = Student.objects.filter(sex=1)                                                               

In [19]: res                                                                                               
Out[19]: <QuerySet [<Student: donghao-25>, <Student: xinlan-30>, <Student: weigang-22>, <Student: moran-0>]

改:

  改一条数据:

  

In [20]: s =Student.objects.get(name=xinlan)                                                             

In [21]: s                                                                                                 
Out[21]: <Student: xinlan-30>

In [22]: s.age = 16                                                                                        

In [23]: s                                                                                                 
Out[23]: <Student: xinlan-16>

另外一种方法:

In [26]: Student.objects.filter(name=xinlan).update(age=18)                                              
Out[26]: 1

In [27]: Student.objects.get(name=xinlan)                                                                
Out[27]: <Student: xinlan-18>

删除

  

In [31]: s = Student.objects.get(pk=2)                                                                     

In [32]: s                                                                                                 
Out[32]: <Student: xinlan-18>

In [33]: s.delete()                                                                                        
Out[33]: (1, {teacher.Student: 1})

批量删除:

  

In [36]: Student.objects.filter(sex=1).delete()                                                            
Out[36]: (3, {teacher.Student: 3})

 

  

django第六课 模型第一讲

原文:https://www.cnblogs.com/donghao1121/p/10421337.html

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