多表表与表关系 增删改查 admin

今日内容

1. 多表表与表关系
2. 增删改查表数据
3. admin

多表操作

表与表关系

默认指向主键 可能是隐藏主键 djamgo1.1默认级联（models. SET NULL解除级联）

一对一

先建立少的一方

OneToOneField

from django.db import models

# Create your models here.

class Author(models.Model):

    """

    作者表

    一对一

    Author表 au(au_id)关联与AuthorDetail表的nid

    """

    name=models.CharField( max_length=32)

    age=models.IntegerField()

    # authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid",on_delete=models.CASCADE)

    au=models.OneToOneField("AuthorDetail",on_delete=models.CASCADE)

class AuthorDetail(models.Model):

    """

    作者详细信息表

    """

    birthday=models.DateField()

    telephone=models.CharField(max_length=11)

    addr=models.CharField(max_length=64)

    # class Meta:

        # db_table='authordetail' #指定表名

        # ordering = ['-id',]

class Publish(models.Model):

    """

    出版社表

    """

    name=models.CharField( max_length=32)

    city=models.CharField( max_length=32)

class Book(models.Model):

    """

    书籍表

    """

    title = models.CharField( max_length=32)

    publishDate=models.DateField()

    price=models.DecimalField(max_digits=5,decimal_places=2)

    书籍表的字段publishs关联与Publish表的主键

    publishs=models.ForeignKey(to="Publish",on_delete=models.CASCADE,)

    authors=models.ManyToManyField('Author',)

多对1

ForeignKey

ManyToManyField

from django.db import models

# Create your models here.

class Author(models.Model):

    """

    作者表

    """

    name=models.CharField( max_length=32)

    age=models.IntegerField()

    # authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid",on_delete=models.CASCADE)

    au=models.OneToOneField("AuthorDetail",on_delete=models.CASCADE)

class AuthorDetail(models.Model):

    """

    作者详细信息表

    """

    birthday=models.DateField()

    telephone=models.CharField(max_length=11)

    addr=models.CharField(max_length=64)

    # class Meta:

        # db_table='authordetail' #指定表名

        # ordering = ['-id',]

class Publish(models.Model):

    """

    出版社表

    """

    name=models.CharField( max_length=32)

    city=models.CharField( max_length=32)

class Book(models.Model):

    """

    书籍表

    Book表与Author表通过ManyToManyField实现多对多关系

    会生成第3张表  id会自己生成 字段是 表名_id

    通过类或实例化对象找到authors找操作第张表

    """

    title = models.CharField( max_length=32)

    publishDate=models.DateField()

    price=models.DecimalField(max_digits=5,decimal_places=2)

    publishs=models.ForeignKey(to="Publish",on_delete=models.CASCADE,)

    authors=models.ManyToManyField('Author',)

多对多

ManyToManyField

from django.db import models

# Create your models here.

class Author(models.Model):

    """

    作者表

    """

    name=models.CharField( max_length=32)

    age=models.IntegerField()

    # authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid",on_delete=models.CASCADE)

    au=models.OneToOneField("AuthorDetail",on_delete=models.CASCADE)

class AuthorDetail(models.Model):

    """

    作者详细信息表

    """

    birthday=models.DateField()

    telephone=models.CharField(max_length=11)

    addr=models.CharField(max_length=64)

    # class Meta:

        # db_table='authordetail' #指定表名

        # ordering = ['-id',]

class Publish(models.Model):

    """

    出版社表

    """

    name=models.CharField( max_length=32)

    city=models.CharField( max_length=32)

class Book(models.Model):

    """

    书籍表

    Book表与Author表通过ManyToManyField实现多对多关系

    会生成第3张表  id会自己生成 字段是 表名_id

    通过类或实例化对象找到authors找操作第张表

    """

    title = models.CharField( max_length=32)

    publishDate=models.DateField()

    price=models.DecimalField(max_digits=5,decimal_places=2)

    publishs=models.ForeignKey(to="Publish",on_delete=models.CASCADE,)

    authors=models.ManyToManyField('Author',)

增删改查表数据

创建表代码

from django.db import models

# Create your models here.

class Author(models.Model):

    """

    作者表

    """

    name=models.CharField( max_length=32)

    age=models.IntegerField()

    # authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid",on_delete=models.CASCADE)

    au=models.OneToOneField("AuthorDetail",on_delete=models.CASCADE)

    def __str__(self):

        return self.name

class AuthorDetail(models.Model):

    """

    作者详细信息表

    """

    birthday=models.DateField()

    telephone=models.CharField(max_length=11)

    addr=models.CharField(max_length=64)

    # class Meta:

        # db_table='authordetail' #指定表名

        # ordering = ['-id',]

    def __str__(self):

        return self.telephone + self.addr

class Publish(models.Model):

    """

    出版社表

    """

    name=models.CharField( max_length=32)

    city=models.CharField( max_length=32)

    def __str__(self):

        return self.name

class Book(models.Model):

    """

    书籍表

    """

    title = models.CharField( max_length=32)

    publishDate=models.DateField()

    price=models.DecimalField(max_digits=5,decimal_places=2)

    publishs=models.ForeignKey(to="Publish",on_delete=models.CASCADE,)

    authors=models.ManyToManyField('Author',)

    def __str__(self):

        return self.title

app01 author 作家表

app01 authordetail 作家详细信息

app01 book表

app01 book authors表 第3张表 book作者表

app01 publish表 出版社

增加

一对一

第一种方式

models.Author.objects.create(

    name='海狗',

    age=59,

    au_id=4

)

第2种方式(与id为4的就是一对一关系)ghj

au_obj = models.AuthorDetail.objects.get(id=4)

第一种方式

models.Author.objects.create(

    name='海狗',

    age=59,

    au=au_obj

)

一对多

pub_obj = models.Publish.objects.get(id=3)

models.Book.objects.create(

    title='xx2',

    price=13,

    publishDate='2011-11-12',

    # publishs=pub_obj , #类属性作为关键字时,值为model对象

    publishs_id=3  # 如果关键字为数据库字段名称,那么值为关联数据的值

)

多对多  -- 多对多关系表记录的增加

ziwen = models.Author.objects.get(id=3)

haigou = models.Author.objects.get(id=5)

new_obj = models.Book.objects.create(

    title='海狗产后护理第二部',

    price=0.5,

    publishDate='2019-09-29',

    publishs_id=2,

)

new_obj.authors.add(3, 5)  # #*args  **kwargs

new_obj.authors.add(*[3, 5])  # 用的最多,

new_obj.authors.add(ziwen, haigou)

删除

# 一对一

# models.AuthorDetail.objects.filter(id=3).delete()

# models.Author.objects.filter(id=3).delete()

# 一对多

# models.Publish.objects.filter(id=3).delete()

# models.Book.objects.filter(id=4).delete()

# 多对多

book_obj = models.Book.objects.get(id=2)

# book_obj.authors.add()  # 添加

# book_obj.authors.remove(1)  #删除

# book_obj.authors.clear()  # 清除

# book_obj.authors.set(['1','5'])  # 先清除再添加,相当于修改

改

    # 改

    # ret = models.Publish.objects.get(id=2)

    # models.Book.objects.filter(id=5).update(

    #     # title='华丽丽',

    #     publishs=ret,

    #     # publishs_id=1,

    # )

跨表查询

    # 查询

    # 一对一

    # 关系属性写在表1,关联到表2,那么通过表1的数据去找表2的数据,叫做正向查询,返过来就是反向查询

    # 查询一下王洋的电话号码

    # 正向查询  对象.属性

    # obj = models.Author.objects.filter(name='王洋').first()

    # ph = obj.au.telephone

    # print(ph)

    # 查一下电话号码为120的作者姓名

    # 反向查询  对象.小写的表名

    # obj = models.AuthorDetail.objects.filter(telephone=120).first()

    # ret = obj.author.name  #陈硕

    # print(ret)

    # 一对多

    # 查询一下 海狗的怂逼人生这本书是哪个出版社出版的  正向查询

    # obj = models.Book.objects.filter(title='海狗的怂逼人生').first()

    # ret = obj.publishs.name

    # print(ret)  #24期出版社

    #  查询一下 24期出版社出版过哪些书

    # obj = models.Publish.objects.filter(name='24期出版社').first()

    #

    # ret = obj.book_set.all() #<QuerySet [<Book: 母猪的产后护理>, <Book: 海狗的怂逼人生>]>

    # for i in ret:

    #     print(i.title)

    # 多对多

    # 海狗的怂逼人生 是哪些作者写的 -- 正向查询

    # obj = models.Book.objects.filter(title='海狗的怂逼人生').first()

    # ret = obj.authors.all()

    #

    # print(ret)  #<QuerySet [<Author: 王洋>, <Author: 海狗>]>

    # for i in ret:

    #     print(i.name)

    # 查询一下海狗写了哪些书 -- 反向查询

    # obj = models.Author.objects.filter(name='海狗').first()

    # ret = obj.book_set.all()

    # print(ret)

    # for i in ret:

    #     print(i.publishs.name)

    #     print(i.title)

    # return HttpResponse('ok')

admin添加用户

python manage.py createsuperuser

输入用户名:wuchao

邮箱不用输 直接回车

输入密码:必须超过8位,并且别太简单

admin注册

from django.contrib import admin

# Register your models here.

from app01 import models

admin.site.register(models.Author)

admin.site.register(models.AuthorDetail)

admin.site.register(models.Publish)

admin.site.register(models.Book)

admin添加用户

python manage.py createsuperuser

输入用户名:wuchao

邮箱不用输 直接回车

输入密码:必须超过8位,并且别太简单

admin注册

from django.contrib import admin

# Register your models here.

from app01 import models

admin.site.register(models.Author)

admin.site.register(models.AuthorDetail)

admin.site.register(models.Publish)

admin.site.register(models.Book)