路飞学城Python-Day101

57-多表操作之一对多添加纪录

def add(request):

# pub = Publish.objects.create(name='人民出版社', email='873245193@qq.com', city='扬州')

# 为book表绑定关系，绑定和publish表的关系

# ------------------方式一和方式二都是绑定一对多的关系

# 方式一

# book_obj = Book.objects.create(title='金瓶', price=100, publishDate="2018-10-05", publish_id=1)

# print(book_obj)

# 方式二 找到实例的对象后直接赋值

# pub_obj = Publish.objects.filter(nid=1).first()

# book_obj = Book.objects.create(title='三体2', price=996, publishDate="2018-10-03", publish=pub_obj)

# print(book_obj.title)

# print(book_obj.publish.name)

# -----------------------------------

# 查询西游记的出版社对应的邮箱

# book_obj = Book.objects.filter(title="西游记").first()

# book_obj_pub = book_obj.publish.email

# print(book_obj_pub)

# +-------------------------------+

# 建立多对多的关系

# book_obj = Book.objects.create(title='暗网', price=100, publishDate="2018-10-06", publish_id=1)

# boy = Author.objects.get(nid=2)

# panda = Author.objects.get(nid=1)

# 多对多关系使用的是many2many的操作的话是不能直接操作表的记录的，必须通过Django的接口去做

# book_obj.authors.add(boy, panda)

# +------其他玩法-------+

# book_obj.authors.add(1, 2, 3) = book_obj.authors.add(*[1, 2, 3])

# 解除多对多的关系(首先必须有多对多的关系)

# book = Book.objects.filter(nid=8).first()

# book.authors.remove(2)

# 清除全部

# book.authors.clear()

return HttpResponse('OK')

 

 

58-多表操作之多对多添加纪录

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59-基于对象的跨表查询简介

跨表查询比单表查询要多得多，一般表很少有单表，更多的都是多表之间互相关联的关系

ORM中的查询是最复杂也最难实现的地方，需要多注意

60-基于对象跨表查询之一对多

使用什么方式的查询都需要视情况而定，本身是需要灵活应用的

# 1.基于对象查询

# 查询一本书的出版社的名字

# 一对多的正向查询

# book_obj = Book.objects.filter(title="三体2").first()

# print(book_obj.publish.name)

# 一对多的反向查询

# 查询对应出版社的书籍

pub_obj = Publish.objects.filter(name='人民出版社').first()

pub_book_name = pub_obj.book_set.all()

# print(pub_book_name)

for name in pub_book_name:

print(name)

 

 

61-基于对象跨表查询之多对多

# 2.多对多的查询的正向查询

# 查询书的作者的名称

# book_obj = Book.objects.filter(title="暗网").first()

# print(book_obj)

# book_obj_author = book_obj.authors.all()

# print(book_obj_author)

# for name in book_obj_author:

# print(name)

# 查找出版过的所有的书籍名称

# author_name = Author.objects.filter(name='panda').first()

# book_list = author_name.book_set.all()

# for book in book_list:

# print(book.title)

 

 

62-基于对象跨表查询之一对一

# 一对一的查询

# 查询一个作者的手机号

# author_num = Author.objects.filter(name="panda").first()

# print(author_num.authordetail.telephone)

# ad = AuthorDeatil.objects.filter(telephone=110).first()

# print(ad.author.name)

 

 

63-基于对象跨表查询的sql语句

64-基于双下划线的跨表查询之一对多1

65-基于双下划线的跨表查询之一对多2

66-基于双下划线的跨表查询之多对多1

67-基于双下划线的跨表查询之多对多2

68-基于双下划线的跨表查询之一对一

# 2.多对多的查询的正向查询

# 查询书的作者的名称

# book_obj = Book.objects.filter(title="暗网").first()

# print(book_obj)

# book_obj_author = book_obj.authors.all()

# print(book_obj_author)

# for name in book_obj_author:

# print(name)

# 查找出版过的所有的书籍名称

# author_name = Author.objects.filter(name='panda').first()

# book_list = author_name.book_set.all()

# for book in book_list:

# print(book.title)

# +-----------------------------------------------------------+

# 一对一的查询

# 查询一个作者的手机号

# author_num = Author.objects.filter(name="panda").first()

# print(author_num.authordetail.telephone)

# ad = AuthorDeatil.objects.filter(telephone=110).first()

# print(ad.author.name)

# +-----------------------------------------------------------+

# 基于双下滑线的跨表查询(join查询)

# 正向查询按字段，反向查询按表名小写用来告诉orm引擎join哪张表

# book_obj = Book.objects.filter(title="暗网").values("publish__name")

# for k in book_obj:

# print(k['publish__name'])

# 方式2

# ret = Publish.objects.filter(book__title="暗网").values("name")

# for i in ret:

# print(i['name'])

# +-----------------------------------------------------------+

# 多对多查询

# 必须告诉引擎通过什么方式来join表中的字段

# 通过Book表join与其关联的Author表

# ret = Book.objects.filter(title="暗网").values("authors__name")

# print(ret)

# 方式二

# ret = Author.objects.filter(book__title="暗网").values("name")

# print(ret)

# +-----------------------------------------------------------+

# 一对一查询

# ret = Author.objects.filter(name='panda').values('authordetail__telephone')

# print(ret)

# ret = AuthorDeatil.objects.filter(author__name="panda").values("telephone")

# print(ret)