标签：jcs get with model 聚合 imp pre set max
方式一：传入Author对象
book = Book.objects.get(bid=1)
gy = Author.objects.get(name="gy")
yq = Author.objects.get(name="yq")
book.authors.add(gy, yq)运行结果：
方式二：传入Author主键
book = Book.objects.get(bid=2)
book.authors.add(3, 4)运行结果：
book = Book.objects.get(bid=1)
book.authors.remove(2) # 移除单个运行结果：
book = Book.objects.get(bid=2)
book.authors.clear() # 移除所有运行结果：
跨表查询：
A—B，关联属性在A表中
正向查询：A----->B，通过字段查询
# 查询《坏蛋是怎样炼成的》这本书的出版社
>>> book = Book.objects.get(title="坏蛋是怎样炼成的")
>>> print(book.publish)
中国城市出版社反向查询：B----->A，通过 表名(小写)_set.all()查询
# 查询中国城市出版社所有书籍
>>> publish = Publish.objects.get(name="中国城市出版社")
>>> book_list = publish.book_set.all()
>>> print(book_list)
<QuerySet [<Book: 坏蛋是怎样炼成的>, <Book: 斗罗大陆>]>正向查询：
# 查询作者gy的电话号码
>>> gy = Author.objects.get(name="gy")
>>> print(gy.author_detail.telephone)
123反向查询：通过表名
# 查询电话号码是456的作者名字
>>> author_detail = AuthorDetail.objects.get(telephone=456)
>>> print(author_detail.author.name)
yq正向查询：
# 查询《斗罗大陆》作者名字和生活的城市
>>> book_obj = Book.objects.get(title="斗罗大陆")
>>> authors = book_obj.authors.all()
>>> for i in authors:
print(i.name, i.author_detail.addr)
糖加三勺 北京反向查询：
# 查询天蚕土豆出过的书籍名字
>>> author = Author.objects.get(name="天蚕土豆")
>>> books = author.book_set.all()
>>> print(books)
<QuerySet [<Book: 斗破苍穹>]>正向查询：
# 查询《坏蛋是怎样炼成的》这本书的出版社
>>> Book.objects.filter(title="坏蛋是怎样炼成的").values("publish__name")
<QuerySet [{‘publish__name‘: ‘中国城市出版社‘}]>反向查询：
# 查询《坏蛋是怎样炼成的》这本书的出版社
>>> Publish.objects.filter(book__title="坏蛋是怎样炼成的").values("name")
<QuerySet [{‘publish__name‘: ‘中国城市出版社‘}]>正向查询：
# 查询《斗罗大陆》作者名字和生活的城市
>>> Book.objects.filter(title="斗罗大陆").values("authors__name", "authors__author_detail__addr")
<QuerySet [{‘authors__name‘: ‘糖加三勺‘, ‘authors__author_detail__addr‘: ‘北京‘}]>反向查询：
# 查询《斗罗大陆》作者名字和生活的城市
>>> Author.objects.filter(book__title="斗罗大陆").values("name", "author_detail__addr")
<QuerySet [{‘name‘: ‘糖加三勺‘, ‘author_detail__addr‘: ‘北京‘}]>正向查询
# 查询作者gy的电话号码
>>> Author.objects.filter(name="gy").values("author_detail__telephone")
<QuerySet [{‘author_detail__telephone‘: 123}]>反向查询
# 查询作者gy的电话号码
>>> ret5 = AuthorDetail.objects.filter(author__name="gy").values("telephone")
<QuerySet [{‘telephone‘: 123}]>正向查询
# 查询手机号以10开头的作者出版过的所有书籍名称以及出版社名称
>>> Book.objects.filter(authors__author_detail__telephone__startswith=10).values("title", "publish__name")
<QuerySet [{‘title‘: ‘斗破苍穹‘, ‘publish__name‘: ‘武汉大学出版社‘}, {‘title‘: ‘武动乾坤‘, ‘publish__name‘: ‘北京大学出版社‘}]>反向查询
# 查询手机号以10开头的作者出版过的所有书籍名称以及出版社名称
>>> Author.objects.filter(author_detail__telephone__startswith=10).values("book__title", "book__publish__name")
<QuerySet [{‘book__title‘: ‘斗破苍穹‘, ‘book__publish__name‘: ‘武汉大学出版社‘}, {‘book__title‘: ‘武动乾坤‘, ‘book__publish__name‘: ‘北京大学出版社‘}]>aggregate，返回值不再是queryset,而是字典
>>> from django.db.models import Avg, Max, Min, Count
>>> Book.objects.aggregate(Avg("price"), Max("price"), Min("price"), Count("price"))
{‘price__avg‘: 136.4, ‘price__max‘: Decimal(‘159.00‘), ‘price__min‘: Decimal(‘125.00‘), ‘price__count‘: 5}annotate，返回值依旧是queryset
数据：
# 查询每个职业的平均工资
>>> Employee.objects.values("dep").annotate(Avg("salary"))
<QuerySet [{‘dep‘: ‘副手‘, ‘salary__avg‘: 4000.0}, {‘dep‘: ‘船员‘, ‘salary__avg‘: 3500.0}, {‘dep‘: ‘船长‘, ‘salary__avg‘: 4950.0}]># 查询每一个出版社名字以及出版的书籍数目
>>> Publish.objects.values("pid").annotate(c=Count("book__title")).values("name", "c")
<QuerySet [{‘name‘: ‘中国城市出版社‘, ‘c‘: 2}, {‘name‘: ‘武汉大学出版社‘, ‘c‘: 2}, {‘name‘: ‘北京大学出版社‘, ‘c‘: 1}]>
# 查询每个作者的名字以及出版过的书籍的最高价格
>>> Author.objects.values("nid").annotate(max_p=Max("book__price")).values("name", "max_p")
<QuerySet [{‘name‘: ‘gy‘, ‘max_p‘: Decimal(‘120.00‘)}, {‘name‘: ‘yq‘, ‘max_p‘: Decimal(‘126.00‘)}, {‘name‘: ‘糖加三勺‘, ‘max_p‘: Decimal(‘125.00‘)}, {‘name‘: ‘天蚕土豆‘, ‘max_p‘: Decimal(‘125.00‘)}]>
# 查询每个书籍的名称以及对应的作者个数
>>> Book.objects.values("bid").annotate(author_count=Count("authors__nid")).values("title", "author_count")
<QuerySet [{‘title‘: ‘坏蛋是怎样炼成的‘, ‘author_count‘: 1}, {‘title‘: ‘斗破苍穹‘, ‘author_count‘: 1}, {‘title‘: ‘斗罗大陆‘, ‘author_count‘: 1}, {‘title‘: ‘武动乾坤‘, ‘author_count‘: 1}, {‘title‘: ‘吞噬星空‘, ‘author_count‘: 1}]>标签：jcs get with model 聚合 imp pre set max
原文地址：https://www.cnblogs.com/ExBurner/p/9236490.html
