Django中ORM系统多表数据操作

一,多表操作之添加

1.在seting.py文件中配置数据库连接信息

2.创建数据库关联关系

from django.db import models

# Create your models here.
class Book(models.Model):
    title = models.CharField( max_length=32)
    pub_date=models.DateField()
    price=models.DecimalField(max_digits=5,decimal_places=2)
    publish=models.ForeignKey(to="Publish",to_field="id",on_delete=models.CASCADE,null=True) #创建外键关联,on_delete=models.CASCADE表示级联删除,关联publish表
    authors=models.ManyToManyField("Author",db_table="book2authors") #  创建多对多关联关系表 关联author表
    def __str__(self):
        return self.title

class Publish(models.Model): #创建publish表 创建出版信息表
    name=models.CharField( max_length=32)
    city=models.CharField( max_length=32)
    email=models.CharField(max_length=32)
    def __str__(self):
        return self.name

class Author(models.Model):#创建author表
    name=models.CharField( max_length=32)
    age=models.IntegerField()
    #books=models.ManyToManyField("Book")
    ad=models.OneToOneField("AuthorDetail",null=True,on_delete=models.CASCADE) #创建一对一的关联关系与authordetail作者信息表
    def __str__(self):
        return self.name
class AuthorDetail(models.Model):创建作者信息表
    birthday=models.DateField()
    telephone=models.BigIntegerField()
    addr=models.CharField( max_length=64)
    # author=models.OneToOneField("Author",on_delete=models.CASCADE)
    def __str__(self):
        return str(self.telephone)
'''
class book_authors(models.Model):
    book=models.ForeignKey("Book",on_delete=models.CASCADE)
    author=models.ForeignKey("Author",on_delete=models.CASCADE)
'''

models.py

3 在启动函数时,在数据库中创建setiing.py文件中相应的库

4 在url分发器中配置网页与视图函数的映射关系

5 在视图函数views.py中封装对数据库操作的功能,

from django.shortcuts import render,HttpResponse,redirect

# Create your views here.
from app01 import models

def add(request):

    ################################## 绑定一对多关系 ##############################
    # 方式1:
    #book=models.Book.objects.create(title="linux",price=122,pub_date="2012-12-12",publish_id=1)

    # 方式2:
    # pub_obj=models.Publish.objects.filter(name="橘子出版社").first()
    # book=models.Book.objects.create(title="php",price=122,pub_date="2012-12-12",publish=pub_obj)
    # print(book.title)
    # print(book.publish_id)
    # print(book.publish) # book书籍出版社对象
    # 查询go出版社的邮箱
    # models.Publish.objects.filter(id= book.publish_id).first().email
    # book.publish.email

    ########################## 绑定多对多的关系;无非是在关系表创建记录 ##########

    # linux这本书绑定两个作者:alex,egon
    # linux=models.Book.objects.filter(title="linux").first()
    # alex=models.Author.objects.filter(name="alex").first()
    # egon=models.Author.objects.filter(name="egon").first()
    # print(linux.price)
    # print(linux.publish)
    #linux.authors.add(alex,egon)
    #linux.authors.add(1)
    #linux.authors.add(*[1,2])
    #linux.authors.remove(alex,egon)
    #linux.authors.clear()
    #linux.authors.set([1,])

    '''
    #KEY:关联属性:authors
    class Book(models.Model):
            title = models.CharField( max_length=32)
            pub_date=models.DateField()
            price=models.DecimalField(max_digits=5,decimal_places=2)
            publish=models.ForeignKey(to="Publish",to_field="id",on_delete=models.CASCADE,null=True)
            authors=models.ManyToManyField("Author",db_table="book2authors") # 创建关系表
            def __str__(self):
                return self.title
    '''

    ###############
    # 正向操作按字段,反向操作按表名小写

    linux = models.Book.objects.filter(title="linux").first()
    go = models.Book.objects.filter(title="go").first()
    alex = models.Author.objects.filter(name="alex").first()
    # 给alex作者绑定两本书籍: linux,go
    alex.book_set.add(linux,go)

    return HttpResponse("添加成功!")

def query(request):
    '''
    一 基于对象的跨表查询( 子查询:以上一次的查询结果作为下一次的查询条件)
       (1)一对多
                         正向查询:按字段 book.publish
         Book对象    ---------------------------------- >  Publish 对象
                      <---------------------------------
                        反向查询:按表名小写_set.all()


        (2)多对多
                       正向查询:按字段 book.authors.all()
         Book对象    ---------------------------------- >  Author 对象
                      <---------------------------------
                        反向查询:按表名小写_set.all()


        (2)一对一
                        正向查询:按字段 book.ad
         Author 对象   ---------------------------------- >  AuthorDetail 对象
                      <---------------------------------
                        反向查询:按表名小写

    二 基于双下划綫的跨表查询:

       KEY:通知ORM引擎如何跨表: 正向查询按字段,反向查询按表名小写

    :param request:
    :return:
    '''
    #################################一基于对象的跨表查询#######################
    #(1)一对多

    # 1 查询linux这本书籍的出版社的地址
    # book=models.Book.objects.filter(title="linux").first()
    # print(book.publish.city)
    # 2 查询苹果出版社出版的所有书籍
    # publish=models.Publish.objects.filter(name="苹果出版社").first()
    # queryset=publish.book_set.all()
    # print(queryset) # <QuerySet [<Book: linux>, <Book: python>]>


    # (2)多对多

    # 1 查询linux书籍的所有作者
    # linux=models.Book.objects.filter(title="linux").first()
    # queryset=linux.authors.all() # <QuerySet [<Author: alex>]>
    # print(queryset)
    # 2 查询alex作者出版过得所有书籍
    # alex=models.Author.objects.filter(name="alex").first()
    # queryset=alex.book_set.all()
    # print(queryset) # <QuerySet [<Book: linux>, <Book: go>]>

   # (3)一对一
    # 1  查询alex的手机号
    # alex = models.Author.objects.filter(name="alex").first()
    # print(alex.ad.telephone)

    # 2 查询手机号为911的作者的名字
    # ad=models.AuthorDetail.objects.filter(telephone=911).first()
    # print(ad.author.name)
    ######################基于双下划线的跨表查询(join查询)#################################
    # 1 查询linux这本书籍的出版社的地址
    '''
    SELECT app01_publish.city from app01_book INNER JOIN app01_publish 
                                  ON app01_book.publish_id = app01_publish.id 
                                  WHERE app01_book.title ="linux"
    
    '''
    # 方式1
    # queryset=models .Book.objects.filter(title="linux").values("price","publish__city")
    # print(queryset)
    # # 方式2
    # queryset=models.Publish.objects.filter(book__title="linux").values("city")
    # print(queryset)

    # 2 查询linux书籍的所有作者
    #queryset=models.Book.objects.filter(title="linux").values("authors__name")
    #queryset=models.Book.objects.filter(title__startswith="l").values("authors__name") # ********
    #print(queryset) # <QuerySet [{'authors__name': 'alex'}, {'authors__name': 'alex'}, {'authors__name': 'egon'}]>

    # queryset=models.Author.objects.filter(book__title="linux").values("name")

    # 3  查询alex的手机号

    # queryset=models.Author.objects.filter(name="alex").values("ad__telephone")
    # queryset=models.AuthorDetail.objects.filter(author__name="alex").values("telephone")
    # print(queryset) # <QuerySet [{'telephone': 110}]>

    # 连续跨表
    # 4 查询人民出版社出版过的所有书籍的名字以及作者的姓名
    # queryset=models.Book.objects.filter(publish__name="人民出版社").values("title","authors__name")
    # models.Author.objects.filter(book__publish__name="人民出版社").values("book__title","name")
    # 5 手机号以151开头的作者出版过的所有书籍名称以及出版社名称
    queryset=models.Book.objects.filter(authors__ad__telephone__contains="1").values("title","publish__name")
    print(queryset)
    return HttpResponse("查询成功!")

6 刷新网页来测试数据库相关功能

Django中ORM系统多表数据操作

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