Django-ORM进阶操作01

• 1.增删改查
• 2.一般操作:

models.UserInfo.objects.filter(id__gt=1)
models.UserInfo.objects.filter(id__lt=1)
models.UserInfo.objects.filter(id__lte=1)
models.UserInfo.objects.filter(id__gte=1)
models.UserInfo.objects.filter(id__in=[1,2,3])
models.UserInfo.objects.filter(id__range=[1,2])
models.UserInfo.objects.filter(name__startswith='au')
models.UserInfo.objects.filter(name__contains='au') # 包含
models.UserInfo.objects.exclude(id=1) # 排除，除去括号内的条件之外的内容。 

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• 3.排序:

user_object_list = models.UserInfo.objects.all().order_by('id') # asc

user_object_list = models.UserInfo.objects.all().order_by('-id') # desc

user_object_list = models.UserInfo.objects.all().order_by('-id','name') # 如果遇到id相等 按name从小到大排序

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• 4.分组:

    from django.db.models import Count

    v = models.UserInfo.objects.values('ut_id').annotate(aa = Count('id'))
    print(v.query)
    # SELECT "app01_userinfo"."ut_id", COUNT("app01_userinfo"."id") AS "aa" FROM "app01_userinfo" GROUP BY "app01_userinfo"."ut_id"

    for item in v:
        print(item)

    v = models.UserInfo.objects.values('ut_id').annotate(aa = Count('id')).filter(aa__gte=2)
    v = models.UserInfo.objects.filter(id__gt=2).values('ut_id').annotate(aa = Count('id')).filter(aa__gte=2)
    # filter()放在前面相等于where 放在annotate后相当于having

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• 5.F, Q, extra

    # F 更新时获取原变量数值

    from django.db.models import F,Q

    models.UserInfo.objects.all().update(age=F('age')+1)

    user_List = models.UserInfo.objects.filter(id__lt=20).values('age')
    for row in user_List:
        print(row['age'])
    from django.db.models import Q



    models.UserInfo.objects.filter(id=1,name='spring')
    condition = {
        'id':1,
        'name':'spring',
    }
    v = models.UserInfo.objects.filter(**condition)




    from django.db.models import Q

---

• Q 用于构造复杂的查询条件

    # Q 用于构造复杂的查询条件

    # Q 的第一种写法
    models.UserInfo.objects.filter(Q(id=1))
    models.UserInfo.objects.filter(Q(id=1) | Q(id=2))
    models.UserInfo.objects.filter(Q(id=3) & Q(id=4))

    # Q 的第二种写法
    q1 = Q()
    q1.connector = 'OR'
    q1.children.append(('id',1))
    q1.children.append(('id',10))
    q1.children.append(('id',9))

    q2 = Q()
    q2.connector = 'OR'
    q2.children.append(('ut_id',1))
    q2.children.append(('ut_id',2))

    con = Q()
    con.add(q1,'AND')
    con.add(q2,'AND')

---

• extra

    # extra


    v = models.UserInfo.objects.all().extra(select={'n':'select count(1) from app01_userinfo'})

    v = models.UserInfo.objects.all().extra(select={'n':'select count(1) from app01_userinfo WHERE id > 100'})

    v = models.UserInfo.objects.all().extra(select={'n':'select count(1) from app01_userinfo WHERE id > %s'},select_params=[100,])
    v = models.UserInfo.objects.all().extra(select={'n':'select count(1) from app01_userinfo WHERE id = %s or id = %s' },select_params=[100,201])

    v = models.UserInfo.objects.all().extra(select={
    'n':'select count(1) from app01_userinfo WHERE id = %s or id = %s' ,
    'm':'select count(1) from app01_userinfo WHERE id = %s or id = %s' ,
    },
    select_params=[3,4,100,201])


    v = models.UserInfo.objects.extra(
        where=['id=%s or id=2','name=%s'],
        params=[1,'summer'],
        order_by=['-id']
    )


    v = models.UserInfo.objects.extra(
        tables=['app01_usertype'],  # 笛卡尔基
        where=['app01_usertype.id = app01_userinfo.ut_id']
    )

• 原生SQL语句

setting.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'db2': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'db2',
        'USER': 'root',
        'PASSWORD': '',
        'HOST': '',
        'PORT': '',
    }
}



    # 原生 SQL语句

    from django.db import connection,connections
    cursor = connection.cursor() # 用默认default的数据库
    cursor = connections['db2'].cursor() # 使用db2 数据库

    cursor.execute('select * from app01_userinfo WHERE id = %s',[1,])

    row = cursor.fetchone()