今日内容:
1 创建多表模型(详情见代码)
from django.db import models
# Create your models here.
class Publish(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
addr = models.CharField(max_length=64)
email = models.EmailField(null=True)
class AuthorDetail(models.Model):
id = models.AutoField(primary_key=True)
sex = models.IntegerField()
phone = models.CharField(max_length=11)
class Author(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
addr = models.CharField(max_length=64)
author_details = models.OneToOneField(to='AuthorDetail', to_field='id')
class Book(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
price = models.DecimalField(max_digits=5, decimal_places=2)
publish = models.ForeignKey(to='Publish', to_field='id')
authors = models.ManyToManyField(to=Author)
#用了OneToOneField和ForeignKey,模型表的字段,后面会自定加_id
# ManyToManyField会自动创建第三张表
# *************重点
# 一对一的关系:OneToOneField
# 一对多的关系:ForeignKey
# 多对多的关系:ManyToManyField
2 添加表记录
1 一对多新增
-两种方式:
-publish=对象
-publish_id=id
# 一对多增
# 方式一
publish = models.Publish.objects.filter(name='北京出版社').first()
res= models.Book.objects.create(name='红楼梦',price=55.67,publish=publish)
# 方式二
res = models.Book(name='三国演义',price=73.89)
res.publish_id=2
res.save()
# 方式三
res = models.Book.objects.create(name='西游记',price=65,publish_id=4)
2 一对多删除:同单表删除
res = models.Publish.objects.filter(id=4).delete() #由于Publish表与Book表的关系是一对多，所以一旦删除Publish表中的记录，会级联删除Book表中的记录 res = models.Book.objects.filter(name='西游记',price=65).delete()
3 一对多修改:两种方式,可以传对象,可以传id
4 一对一跟一对多一样
# 一对多修改
# 方式一
publish = models.Publish.objects.filter(name='东京出版社').first()
res = models.Book.objects.filter(publish=publish).update(price=99)
# 方式二
res = models.Book.objects.filter(publish_id=3).update(price=58)
# 方式三
res = models.Book.objects.filter(publish_id=3).first()
res.price = 73.59
res.save()
5 多对多:
-add ----->可以传对象,可以传id,可以传多个
-remove ----->可以传对象,可以传id,可以传多个
-clear ---->没有参数
-set ----->跟上面不一样,必须传列表,列表里面可以是对象,可以是id
# 多对多增
# 方式一
book = models.Book.objects.filter(name='红楼梦').first()
user1 = models.Author.objects.filter(id=1).first()
user2 = models.Author.objects.filter(id=2).first()
book.authors.add(user1, user2)
# 方式二
book = models.Book.objects.filter(name='三国演义').first()
book.authors.add(2,3)
# 多对多删除
# 方式一
book = models.Book.objects.filter(name='三国演义').first()
user = models.Author.objects.filter(id=3).first()
book.authors.remove(user)
# 方式二
book = models.Book.objects.filter(name='红楼梦').first()
book.authors.remove(3)
# clear
book = models.Book.objects.filter(name='红楼梦').first()
book.authors.clear()
# set
book = models.Book.objects.filter(name='红楼梦').first()
book.authors.set([1,2,3])
3 基于对象的跨表查询
1 一对一
正向:正向查询按字段
反向:反向查询按表名小写
# 一对一
# 正向
author = models.Author.objects.filter(id=1).first()
res = author.author_details
print(res.phone)
# 反向
authordetail = models.AuthorDetail.objects.filter(id=3).first()
res = authordetail.author
print(res.addr)
2 一对多
正向:正向查询按字段
反向:反向按表名小写_set.all()
# 一对多
# 正向
book = models.Book.objects.filter(id=2).first()
res = book.publish
print(res)
# 反向
publish = models.Publish.objects.filter(name='北京出版社').first()
res = publish.book_set.all()
print(res)
3 多对多
正向:正向查询按字段
反向查询:反向按表名小写_set.all()
# 多对多
# 正向
book = models.Book.objects.filter(id=2).first()
res = book.authors.all()
print(res)
# 反向
author = models.Author.objects.filter(id=1).first()
res = author.book_set.all()
print(res)
4******基于对象的查询,多次查询(子查询)
publish = models.Publish.objects.filter(id=1).first()
book = publish.book_set.filter(name='红楼梦').first()
author = book.authors.filter(name='郑棒').first()
authordetail = author.author_details
print(authordetail.phone)
4 基于双下划线的跨表查询
-连表查询
-一对一双下划线查询
-正向:按字段,跨表可以在filter,也可以在values中
res = models.Author.objects.filter(name='郑棒').values('author_details__phone', 'author_details__sex')
print(res)
-反向:按表名小写,跨表可以在filter,也可以在values中
res = models.AuthorDetail.objects.filter(author__name='郑棒').values('phone','author__addr')
print(res)