F and Q:

models：

Book class (models.Model): 
    name = models.CharField (= 32 MAX_LENGTH, the verbose_name = "title") 
    #define Price: 
    . price = models.DecimalField (max_digits =. 5, decimal_places = 2) is the maximum # 99999.99 yuan 
    #define sales: 
    would like to purchase = models.IntegerField (default = 0) 
    # define inventory: 
    kucun = models.IntegerField (default = 100) 
    Pub = models.ForeignKey (Publisher, null = True, on_delete = models.CASCADE, the related_name = 'Books', 
                            = related_query_name 'Book') 

F. and Q:

os Import 
os.environ.setdefault ( "DJANGO_SETTINGS_MODULE", "about_orm.settings") 
Import Django 
django.setup () 
from app01 Import Models 
from django.db.models Import F, Q 
# get stock: 
RET = models.Book. objects.filter (sale__gt = F. ( "kucun")) 
# make sales multiplied by 2: 
RET = models.Book.objects.update (Sale = F. ( "Sale") * 2) 
# pk get greater than 3 and less than 2 a comma, or by |, and & is, non ~: 
RET = models.Book.objects.filter (Q (= pk__gt. 3) | Q (pk__lt = 2))