模型层

​ ORM操作

# 单表查询表
class User(models.Model):name = models.CharField(max_length=32)age = models.IntegerField()register_time = models.DateField()

# 多表查询表
class Book(models.Model):title = models.CharField(max_length=32)price = models.DecimalField(max_digits=8,decimal_places=2)publish_date = models.DateField(auto_now_add=True)# 外键关系publish = models.ForeignKey(to='Publish')   # 一对多关系authors = models.ManyToManyField(to='Author')  # 多对多关系class Publish(models.Model):name = models.CharField(max_length=32)addr = models.CharField(max_length=32)email = models.EmailField()  # 对应就是varchar类型class Author(models.Model):name = models.CharField(max_length=32)age = models.IntegerField()authordetail = models.OneToOneField(to='AuthorDetail')  # 一对一关系class AuthorDetail(models.Model):phone = models.CharField(max_length=32)addr = models.CharField(max_length=32)

单表查询

# 新增数据
'''基于 create 创建user_obj = models.User.objects.create(name="Ethan", age=18, register_time="2019-6-12")基于对象的绑定方法创建user_obj = models.User(name="Jason", age=88, register_time="2019-6-6")user_obj.save()from datetime import datetimecurrent_time = datetime.now()models.User.objects.create(name="Bilibili",age=20, register_time=current_time)'''

# 修改数据
"""基于对象user_obj = models.User.objects.filter(name="Ethan").first()user_obj.age = 21user_obj.save()基于 querysetuser_obj = models.User.objects.filter(name="Ethan").update(age=22)
"""

# 删除数据
"""基于 querysetmodels.User.objects.filter(name="Jason").delete()基于对象user_obj = models.User.objects.filter(name="Jason").first()user_obj.delete()
"""

# 查询数据
"""# all() 返回全部数据,为queryset类型result = models.User.objects.all()print(result)# filter(**kwargs) 条件查询，返回querysetresult = models.User.objects.filter(name="Bilibili")print(result)# get(**kwargs) 与filter一样都是条件查询,直接返回对象，但匹配不到数据则报错，不建议使用result = models.User.objects.get(name="Ethan")print(result)# exclude(**kwargs) 返回非满足条件的对象result = models.User.objects.exclude(name="Ethan")print(result)# order_by(*field_name) 根据字段名排序,默认升序，加负号则降序result = models.User.objects.order_by("age")print(result)result = models.User.objects.order_by("-age")print(result)# reverse() 在被 order_by() 后使用，反序result = models.User.objects.order_by("age").reverse()print(result)# count() 返回查询数据的条数# result = models.User.objects.count()# result = models.User.objects.all().count()result = models.User.objects.filter(name="Ethan").count()print(result)# first() 返回第一个数据对象result = models.User.objects.first()print(result)result = models.User.objects.last()     # 返回最后一个对象print(result)result = models.User.objects.all()[0]   # 不支持负索引print(result)# exists() 判断数据是否为空result = models.User.objects.all().exists()print(result)result = models.User.objects.filter(name="BB").exists()print(result)# values() 以列表套字典的形式返回对应字段名的值result = models.User.objects.values("name")print(result)result = models.User.objects.values("name", "age")print(result)# values_list() 以列表套元组的形式返回对应字段名的值result = models.User.objects.values_list("name", "age")print(result)# distinct() 去重result = models.User.objects.all().distinct()print(result)
"""

# 双下划线查询
"""# 查询年纪大于30岁的用户result = models.User.objects.filter(age__gt=30)print(result)# 查询年纪小于30岁的用户result = models.User.objects.filter(age__lt=30)print(result)# 查询年纪大于等于20岁的用户result = models.User.objects.filter(age__gte=20)print(result)# 查询年纪小于等于20岁的用户result = models.User.objects.filter(age__lte=20)print(result)# 查询年纪为20或22或30的用户result = models.User.objects.filter(age__in=[20, 22, 30])print(result)# 查询年纪在20~30岁之间的用户result = models.User.objects.filter(age__range=[20, 30])print(result)# 查询指定日注册的用户result = models.User.objects.filter(register_time__day=12)print(result)# 查询名字中包含字母b的用户result = models.User.objects.filter(name__contains="n")     # 区别大小写print(result)result = models.User.objects.filter(name__icontains="n")    # 不区分大小写print(result)# 查询名字以Eth开头的用户result = models.User.objects.filter(name__startswith="Eth")   # 区分大小写print(result)# 查询名字以li结尾的用户result = models.User.objects.filter(name__endswith="li")print(result)
"""

多表查询

一对多

# 新增数据
"""直接写 idmodels.Book.objects.create(title="火影", price=99.9, publish_id=1)传数据对象publish_obj = models.Publish.objects.filter(pk=2).first()models.Book.objects.create(title="海贼王", price=88.8, publish=publish_obj)
"""
# 修改数据
"""queryset 修改models.Book.objects.filter(pk=3).update(publish_id=1)  # 传idpublish_obj = models.Publish.objects.filter(pk=1).first()models.Book.objects.filter(pk=2).update(publish=publish_obj)  # 传对象对象修改book_obj = models.Book.objects.filter(pk=2).first()book_obj.publish_id = 2  # 传idbook_obj.save()book_obj = models.Book.objects.filter(pk=2).first()publish_obj = models.Publish.objects.filter(pk=1).first()book_obj.publish = publish_obj  # 传对象book_obj.save()
"""
# 删除数据
"""queryset删除models.Book.objects.filter(pk=2).delete()models.Publish.objects.filter(pk=1).delete()对象删除book_obj = models.Book.objects.filter(pk=2).first()book_obj.delete()
"""

多对多

# 添加绑定关系 add
# add支持传数字或者对象，并且可以传多个
"""直接绑定idbook_obj = models.Book.objects.filter(pk=2).first()book_obj.authors.add(1)book_obj.authors.add(2,3)直接绑定对象book_obj = models.Book.objects.filter(pk=3).first()author_obj = models.Author.objects.filter(pk=5).first()author_obj2 = models.Author.objects.filter(pk=2).first()author_obj3 = models.Author.objects.filter(pk=1).first()book_obj.authors.add(author_obj)book_obj.authors.add(author_obj2, author_obj3)
"""
# 修改绑定关系 set
#  set(args)  args必须为可迭代对象
"""直接通过id修改book_obj = models.Book.objects.filter(pk=3).first()book_obj.authors.set((5,))book_obj.authors.set((1, 2, 3))  # 先清空后修改直接通过对象修改单个修改book_obj = models.Book.objects.filter(pk=2).first()author_obj = models.Author.objects.filter(pk=1).all()book_obj.authors.set(author_obj)批量修改author_obj2 = models.Author.objects.filter(pk=2).first()author_obj3 = models.Author.objects.filter(pk=3).first()author_obj4 = models.Author.objects.filter(pk=5).first()book_obj.authors.set((author_obj2, author_obj3, author_obj4))
"""
# 删除绑定关系 remove
"""通过id删除book_obj = models.Book.objects.filter(pk=3).first()#book_obj.authors.remove(1)# book_obj.authors.remove(2,3)通过对象删除book_obj = models.Book.objects.filter(pk=3).first()author_obj = models.Author.objects.all().first()book_obj.authors.remove(author_obj) # 单个删除author_list = models.Author.objects.all() # 批量删除book_obj.authors.remove(*author_list)  # 需要将queryset打散
"""
# 清空 clear()
"""book_obj = models.Book.objects.filter(pk=3).first()book_obj.authors.clear()
"""

# 基于对象的表查询
"""正向查询"""
"""查询书籍是火影忍者的出版社邮箱book_obj = models.Book.objects.filter(title="火影").first()email = book_obj.publish.emailprint(email)查询书籍是口袋妖怪的作者的姓名book_obj = models.Book.objects.filter(title="口袋妖怪").first()name = book_obj.authors  # app03.Author.Nonename = book_obj.authors.all()print(name)查询作者为阿大的电话号码author_obj = models.Author.objects.filter(name="阿大").first()phone = author_obj.authordetail.phoneprint(phone)
"""
"""反向查询"""
"""查询出版社是Bilibili的书籍         #一对多的反向查询publish_obj = models.Publish.objects.filter(name="Bilibili").first()book = publish_obj.book_set.all()print(book)查询作者阿二写过的所有书籍           #多对多的反向查询author_obj = models.Author.objects.filter(name="阿二").first()books = author_obj.book_set.all()print(books)查询电话号码是999的作者姓名          #一对一的反向查询detail_obj = models.AuthorDetail.objects.filter(phone=999).first()name = detail_obj.author.nameprint(name)
"""

# 基于下划线的查询
"""正向查询"""
"""查询书籍为海贼王的出版社地址address = models.Book.objects.filter(title="海贼王").values('publish__addr')print(address)查询书籍为名侦探柯南的作者的姓名name = models.Book.objects.filter(title="名侦探柯南").values('authors__name')print(name)查询作者为阿三的家乡address = models.Author.objects.filter(name="阿三").values('authordetail__addr')print(address)
"""
"""反向查询"""
"""查询 Cilicili 出版社出版的书籍books = models.Publish.objects.filter(name="Cilicili").values('book__title')print(books)查询 电话号码为 114 的作者姓名name = models.AuthorDetail.objects.filter(phone=114).values('author__name')print(name)查询数据为口袋妖怪的作者的电话号码phone = models.Book.objects.filter(title="口袋妖怪").values('authors__authordetail__phone')print(phone)
"""

# 聚合查询
"""from django.db.models import Max, Min, Count, Sum, Avg查询指定或者所有书籍的作者个数count = models.Book.objects.aggregate(count_num=Count('authors'))count = models.Book.objects.filter(pk=3).aggregate(count_num=Count('authors'))print(count)查询所有出版社出版的书的平均价格avg_price = models.Publish.objects.aggregate(avg_price=Avg('book__price'))print(avg_price)
"""

# 分组查询
"""统计每个出版社出版的书的平均价格price = models.Publish.objects.annotate(price=Avg('book__price')).values('price')print(price)统计各出版社最便宜的书的价格price = models.Publish.objects.annotate(price = Min('book__price')).values('price')print(price)统计每个作者书的总价sum = models.Author.objects.annotate(sum_price=Sum('book__price')).values('sum_price')print(sum)"""