场景：models.py

#coding: utf8import datetimefrom django.db import modelsclass Order(models.Model):    orderid     = models.CharField(max_length=64, unique=True)    desc        = models.CharField(max_length=512)    product     = models.CharField(max_length=512, null=True)    amount      = models.IntegerField()    userid      = models.CharField(max_length=512, null=True)    create_time = models.DateTimeField(db_index=True)

1  F() ---- 专门取对象中某列值的操作

1 from django.db.models import F2 from core.models import Order3  4 order = Order.objects.get(orderid='123456789')5 order.amount = F('amount') - 16 order.save()

对应SQL语句

UPDATE `core_order` SET ..., `amount` = `core_order`.`amount` - 1 WHERE `core_order`.`orderid` = '123456789'

2 Q() ---- 对对象的复杂查询

Q对象(django.db.models.Q)可以对关键字参数进行封装，从而更好地应用多个查询。可以组合使用 &（and）,|（or），~（not）操作符，当一个操作符是用于两个Q的

Python代码：

Order.objects.get(    Q(desc__startswith='Who'),    Q(create_time=date(2016, 10, 2)) | Q(create_time=date(2016, 10, 6)))

对应的sql 语句

SELECT * from core_order WHERE desc LIKE 'Who%' AND (create_time = '2016-10-02' OR create_time = '2016-10-06')

复杂参数：

params = []    username = request.GET.get("username")    isactive = request.GET.get("isblock")    if username:        params.append(models.Q(username__contains=username))    if isactive:        params.append(models.Q(is_block=isactive))    data = get_page_list(Account.objects.filter(*params), page_no=page_no, page_size=12)