day55 django 模型层,orm连表操作

野性酷女 2023-08-17 17:48 144阅读 0赞

# 设计表 #

django之orm详解:

[https://www.cnblogs.com/komorebi/p/11551089.html][https_www.cnblogs.com_komorebi_p_11551089.html]

在django中设计表

1.先在navicat中建好一个库

2.更改django配置中的DATABASES

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DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.mysql',
            'NAME': 'day55',
            'USER':'root',
            'PASSWORD':'123',
            'HOST':'127.0.0.1',
            'POST':3306,
            'CHARSET':'utf8',
        }
    }

settings.py

3.在创建项目中的文件下的migrations文件夹下,找到\_\_init\_\_.py

import pymysql
    pymysql.install_as_MySQLdb()

4.去models文件中创建表

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from django.db import models
    
    # Create your models here.
    class Book(models.Model):
        title = models.CharField(max_length=255)
        price = models.DecimalField(max_digits=8,decimal_places=2)
        publish_data = models.DateField(auto_now_add=True)
    
    
        publish = models.ForeignKey(to='Publish')
        # 默认是跟publish的主键字段做的一对多外键关联
        authors = models.ManyToManyField(to='Author')
        # 虚拟字段  1.自动创建第三表  2.棒orm跨表查询
    
    class Publish(models.Model):
        name = models.CharField(max_length=32)
        addr = models.CharField(max_length=32)
    
    
    class Author(models.Model):
        name = models.CharField(max_length=64)
        age = models.IntegerField()
    
        author_detail = models.OneToOneField(to='AuthorDetail')
    
    
    class AuthorDetail(models.Model):
        phone = models.BigIntegerField()
        addr = models.CharField(max_length=64)

表

5.写数据库迁移命令

![1659204-20190919210650483-1748529017.png][]

![1659204-20190919210755719-1514403827.png][]

之后就开始填写数据,制作测试脚本

from django.test import TestCase
    
    # Create your tests here.
    import os
    
    
    if __name__ == "__main__":
        os.environ.setdefault("DJANGO_SETTINGS_MODULE", "day55.settings")
        import django
        django.setup()
        """
        写针对某一个.py文件的测试代码
        """

from app01 import models

### 增 ###

# publish_id  实际字段传数字
        models.Book.objects.create(title='围城里的男人',price=166.3,publish_data='2016-03-15',publish_id=1)
        # publish 虚拟字段直接传对象  pk 主键
        publish_obj = models.Publish.objects.filter(pk=1).first()
        models.Book.objects.create(title='红玫瑰',price=5555,publish=publish_obj)

![1659204-20190919222742176-1357983349.png][]

### 改 ###

# 改 将id=5 的书的作者id改为4
    # 传数字
    models.Book.objects.filter(pk=5).update(publish=4)

![1659204-20190919225641373-1414993686.png][]

# 传对象  改为3
    publish_obj = models.Publish.objects.filter(pk=3).first()
    # print(publish_obj)
    models.Book.objects.filter(pk=5).update(publish=publish_obj)

![1659204-20190919225832539-962879001.png][]

# 双下滑查询 #

查看orm内部sql语句的方法有哪些  
1.如果是queryset对象 那么可以点query直接查看该queryset的内部sql语句  
2.在django项目的配置文件中 配置一下参数即可实现所有的orm在查询的时候自动打印对应的sql语句

LOGGING = {
        'version': 1,
        'disable_existing_loggers': False,
        handlers': {
         
            'console':{
                'level':'DEBUG',
                'class':'logging.StreamHandler',
            },
        },
        'loggers': {
            'django.db.backends': {
            'handlers': ['console'],
            'propagate': True,
            'level':'DEBUG',
            },
             }
    }

配置好之后，再执行任何对数据库进行操作的语句时，会自动将Django执行的sql语句打印到pycharm终端上

除了配置外，还可以通过一点.query即可查看查询语句

![1659204-20190920165533658-138541775.png][]

转载于:https://www.cnblogs.com/komorebi/p/11550812.html

[https_www.cnblogs.com_komorebi_p_11551089.html]: https://www.cnblogs.com/komorebi/p/11551089.html
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