1 <1> all():                 查询所有结果
 2  
 3 <2> filter(**kwargs):      它包含了与所给筛选条件相匹配的对象
 4  
 5 <3> get(**kwargs):         返回与所给筛选条件相匹配的对象，返回结果有且只有一个，如果符合筛选条件的对象超过一个或者没有都会抛出错误。
 6  
 7 <4> exclude(**kwargs):     它包含了与所给筛选条件不匹配的对象
 8  
 9 <5> values(*field):        返回一个ValueQuerySet——一个特殊的QuerySet，运行后得到的并不是一系列model的实例化对象，而是一个可迭代的字典序列
10  
11 <6> values_list(*field):   它与values()非常相似，它返回的是一个元组序列，values返回的是一个字典序列
12  
13 <7> order_by(*field):      对查询结果排序
14  
15 <8> reverse():             对查询结果反向排序，请注意reverse()通常只能在具有已定义顺序的QuerySet上调用(在model类的Meta中指定ordering或调用order_by()方法)。
16  
17 <9> distinct():            从返回结果中剔除重复纪录(如果你查询跨越多个表，可能在计算QuerySet时得到重复的结果。此时可以使用distinct()，注意只有在PostgreSQL中支持按字段去重。)
18  
19 <10> count():              返回数据库中匹配查询(QuerySet)的对象数量。
20  
21 <11> first():              返回第一条记录
22  
23 <12> last():               返回最后一条记录
24  
25 <13> exists():             如果QuerySet包含数据，就返回True，否则返回False

 1 models.Tb1.objects.filter(id__lt=10, id__gt=1)   # 获取id大于1 且 小于10的值
 2  
 3 models.Tb1.objects.filter(id__in=[11, 22, 33])   # 获取id等于11、22、33的数据
 4 models.Tb1.objects.exclude(id__in=[11, 22, 33])  # not in
 5  
 6 models.Tb1.objects.filter(name__contains="ven")  # 获取name字段包含"ven"的
 7 models.Tb1.objects.filter(name__icontains="ven") # icontains大小写不敏感
 8  
 9 models.Tb1.objects.filter(id__range=[1, 3])      # id范围是1到3的，等价于SQL的bettwen and
10  
11 类似的还有：startswith，istartswith, endswith, iendswith　
12 
13 date字段还可以：
14 models.Class.objects.filter(first_day__year=2017)

1 book_obj = models.Book.objects.first()  # 第一本书对象
2 print(book_obj.publisher)  # 得到这本书关联的出版社对象
3 print(book_obj.publisher.name)  # 得到出版社对象的名称

1 print(models.Book.objects.values_list("publisher__name"))

1 >>> import datetime
2 >>> models.Author.objects.first().book_set.create(title="番茄物语", publish_date=datetime.date.today())

>>> author_objs = models.Author.objects.filter(id__lt=3)
>>> models.Book.objects.first().authors.add(*author_objs)

>>> models.Book.objects.first().authors.add(*[1, 2])

>>> book_obj = models.Book.objects.first()
>>> book_obj.authors.set([2, 3])

>>> book_obj = models.Book.objects.first()
>>> book_obj.authors.remove(3)

>>> book_obj = models.Book.objects.first()
>>> book_obj.authors.clear()

class Book(models.Model):
    title = models.CharField(max_length=32)
    publisher = models.ForeignKey(to=Publisher)

>>> models.Publisher.objects.first().book_set.clear()
Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: 'RelatedManager' object has no attribute 'clear'

class Book(models.Model):
    name = models.CharField(max_length=32)
    publisher = models.ForeignKey(to=Class, null=True)

>>> models.Publisher.objects.first().book_set.clear()

from django.db.models import Avg, Sum, Max, Min, Count

>>> from django.db.models import Avg, Sum, Max, Min, Count
>>> models.Book.objects.all().aggregate(Avg("price"))
{'price__avg': 13.233333}

>>> models.Book.objects.aggregate(average_price=Avg('price'))
{'average_price': 13.233333}

>>> models.Book.objects.all().aggregate(Avg("price"), Max("price"), Min("price"))
{'price__avg': 13.233333, 'price__max': Decimal('19.90'), 'price__min': Decimal('9.90')}

select dept,AVG(salary) from employee group by dept;

from django.db.models import Avg
Employee.objects.values("dept").annotate(avg=Avg("salary").values(dept, "avg")

select dept.name,AVG(salary) from employee inner join dept on (employee.dept_id=dept.id) group by dept_id;

from django.db.models import Avg
models.Dept.objects.annotate(avg=Avg("employee__salary")).values("name", "avg")

>>> book_list = models.Book.objects.all().annotate(author_num=Count("author"))
>>> for obj in book_list:
...     print(obj.author_num)
...
2
1
1

>>> publisher_list = models.Publisher.objects.annotate(min_price=Min("book__price"))
>>> for obj in publisher_list:
...     print(obj.min_price)
...     
9.90
19.90

>>> models.Book.objects.values("publisher__name").annotate(min_price=Min("price"))
<QuerySet [{'publisher__name': '沙河出版社', 'min_price': Decimal('9.90')}, {'publisher__name': '人民出版社', 'min_price': Decimal('19.90')}]>

>>> models.Book.objects.annotate(author_num=Count("author")).filter(author_num__gt=1)
<QuerySet [<Book: 番茄物语>]>

>>> models.Book.objects.annotate(author_num=Count("author")).order_by("author_num")
<QuerySet [<Book: 香蕉物语>, <Book: 橘子物语>, <Book: 番茄物语>]>

>>> models.Author.objects.annotate(sum_price=Sum("book__price")).values("name", "sum_price")
<QuerySet [{'name': '小精灵', 'sum_price': Decimal('9.90')}, {'name': '小仙女', 'sum_price': Decimal('29.80')}, {'name': '小魔女', 'sum_price': Decimal('9.90')}]>

from django.db.models import F
models.Book.objects.filter(commnet_num__gt=F('keep_num'))

models.Book.objects.filter(commnet_num__lt=F('keep_num')*2)

models.Book.objects.all().update(price=F("price")+30)

>>> from django.db.models.functions import Concat
>>> from django.db.models import Value
>>> models.Book.objects.all().update(title=Concat(F("title"), Value("("), Value("第一版"), Value(")")))

models.Book.objects.filter(Q(authors__name="小仙女")|Q(authors__name="小魔女"))

>>> models.Book.objects.filter(Q(author__name="小仙女") & ~Q(publish_date__year=2018)).values_list("title")
<QuerySet [('番茄物语',)]>

>>> models.Book.objects.filter(Q(publish_date__year=2018) | Q(publish_date__year=2017), title__icontains="物语")
<QuerySet [<Book: 番茄物语>, <Book: 香蕉物语>, <Book: 橘子物语>]>

entries = Entry.objects.select_for_update().filter(author=request.user)

 1 import os
 2 
 3 if __name__ == '__main__':
 4     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "BMS.settings")
 5     import django
 6     django.setup()
 7 
 8     import datetime
 9     from app01 import models
10 
11     try:
12         from django.db import transaction
13         with transaction.atomic():
14             new_publisher = models.Publisher.objects.create(name="火星出版社")
15             models.Book.objects.create(title="橘子物语", publish_date=datetime.date.today(), publisher_id=10)  # 指定一个不存在的出版社id
16     except Exception as e:
17         print(str(e))

class Person(models.Model):
    first_name = models.CharField(...)
    last_name = models.CharField(...)
    birth_date = models.DateField(...)

>>> for p in Person.objects.raw('SELECT * FROM myapp_person'):
...     print(p)

ret = models.Student.objects.raw('select id, tname as hehe from app02_teacher')
    for i in ret:
        print(i.id, i.hehe)

d = {'tname': 'haha'}
    ret = models.Student.objects.raw('select * from app02_teacher', translations=d)
    for i in ret:
        print(i.id, i.sname, i.haha)

d = {'tname': 'haha'}
    ret = models.Student.objects.raw('select * from app02_teacher where id > %s', translations=d, params=[1,])
    for i in ret:
        print(i.id, i.sname, i.haha)

from django.db import connection, connections
cursor = connection.cursor()  # cursor = connections['default'].cursor()
cursor.execute("""SELECT * from auth_user where id = %s""", [1])
ret = cursor.fetchone()

 1 import os
 2 
 3 if __name__ == '__main__':
 4     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "BMS.settings")
 5     import django
 6     django.setup()
 7 
 8     from app01 import models
 9 
10     books = models.Book.objects.all()
11     print(books)