Django ORM 多表查询示例代码_python_

# 构建表结构 from django.db import models # 表app01_publish class Publish(models.Model): name = models.CharField(max_length=20) addr = models.CharField(max_length=20) # 表app01_author_detail class Author_Detail(models.Model): tel = models.CharField(max_length=20) # 表app01_author class Author(models.Model): name = models.CharField(max_length=20) age = models.IntegerField() # 表app01_author一对一表app01_authordetail detail = models.OneToOneField(to='Author_Detail',to_field='id',unique=True,on_delete=models.CASCADE) # 表app01_book class Book(models.Model): title = models.CharField(max_length=20) price = models.DecimalField(max_digits=8, decimal_places=2) pub_date = models.DateField(auto_now_add=True) # 表app01_book多对一表app01_publish，参数to指定模型名，参数to_field指定要关联的那个字段 publish = models.ForeignKey(to='Publish',to_field='id',on_delete=models.CASCADE) # 我们自己写sql时，针对书籍表与作者表的多对关系，需要自己创建新表，而基于django的orm，下面这一行代码可以帮我们自动创建那张关系表 authors=models.ManyToManyField(to='Author') # 变量名为authors，则新表名为app01_book_authors，若变量名为xxx，则新表名为app01_book_xxx 

# 添加数据 import os if __name__ == "__main__": os.environ.setdefault("DJANGO_SETTINGS_MODULE", "book_sys.settings") import django django.setup() from app01.models import * # 1、先添加没有外键字段的 author_detail表 pubulish表 Author_Detail.objects.create(tel='123456789') Author_Detail.objects.create(tel='987654321') Author_Detail.objects.create(tel='000000000') Publish.objects.create(name='北方出版社',addr='北京') Publish.objects.create(name='南方出版社',addr='南京') Publish.objects.create(name='东方出版社',addr='上海') Publish.objects.create(name='西方出版社',addr='西安') # 2、添加 author表 book表 Author.objects.create(name='frank',age=31 ,detail_id=1) Author.objects.create(name='lili',age=29 ,detail_id=2) Author.objects.create(name='tank',age=42 ,detail_id=3) Book.objects.create(title='三国演义',price=200 ,publish_id=1) Book.objects.create(title='三国志',price=198.5 ,publish_id=2) Book.objects.create(title='红楼梦',price=255.43 ,publish_id=2) Book.objects.create(title='西游记',price=300.5 ,publish_id=3) Book.objects.create(title='西厢记',price=213.4 ,publish_id=4) Book.objects.create(title='水浒传',price=199 ,publish_id=1) # 3、最后操作 author_book表，由于使用的是 ManyToMany 字段自动生成的，所以要基于外键所在的表进行操作 book_obj1=Book.objects.filter(pk=1).first() book_obj1.authors.add(1,2) book_obj2 = Book.objects.filter(pk=2).first() book_obj2.authors.add(1) book_obj3 = Book.objects.filter(pk=3).first() author_obj1 = Author.objects.filter(pk=1).first() author_obj2 = Author.objects.filter(pk=2).first() book_obj3.authors.add(author_obj1,author_obj2) book_obj4 = Book.objects.filter(pk=4).first() book_obj4.authors.add(3,2) book_obj5 = Book.objects.filter(pk=5).first() book_obj5.authors.add(3) book_obj6 = Book.objects.filter(pk=6).first() book_obj6.authors.add(1,3)

book_obj = Book.objects.filter(pk=5).first() res = book_obj.publish print(res) # Publish object print(res.name) # 西方出版社

book_obj = Book.objects.filter(pk=3).first() res = book_obj.authors print(res) # app01.Author.None

book_obj = Book.objects.filter(pk=3).first() res = book_obj.authors res1 = book_obj.authors.all() print(res1) # , ]>

author_obj = Author.objects.filter(name='lili').first() res = author_obj.detail print(res) print(res.tel)

publish_obj=Publish.objects.filter(name='东方出版社').first() print(publish_obj) # Publish object res = publish_obj.book_set print(res) # app01.Book.None res1 = res.all() print(res1) # ]> for obj in res1: print(obj.title)

author_obj = Author.objects.filter(name='lili').first() res = author_obj.book_set print(res) # app01.Book.None res1 = res.all() print(res1) # , , ]> for obj in res1: print(obj.title, end='') # 三国演义,红楼梦,西游记,

detail_obj = Author_Detail.objects.filter(tel='000000000').first() print(detail_obj) # Author_Detail object res = detail_obj.author print(res) # Author object print(res.name) # tank

res = Author.objects.filter(name='frank').values('detail__tel') print(res) #  print(res.first()) # {'detail__tel': '123456789'}

res = Book.objects.filter(title='三国演义').values('publish__name') print(res) print(res.first()) #  # {'publish__name': '北方出版社'}

res = Book.objects.filter(title='三国演义').values('authors__name') print(res) # 

res = Author_Detail.objects.filter(tel='123456789').values('author__name') print(res) # 

res = Publish.objects.filter(name='北方出版社').values('book__title') print(res) # 

res = Author.objects.filter(name='lili').values('book__title') print(res) # 提示：
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