django框架<三>

一、ORM操作

 1、django orm创建数据库的方法

(1)指定连接pymysql(python3.x),先配置__init__.py

import pymysql
pymysql.install_as_MySQLdb()

(2)、配置连接mysql文件信息

settings.py

DATABASES = {

    'default': {

        'ENGINE': 'django.db.backends.mysql', 

        'NAME': 'django_orm',    #你的数据库名称

        'USER': 'root',   #你的数据库用户名

        'PASSWORD': '', #你的数据库密码

        'HOST': '', #你的数据库主机,留空默认为localhost

        'PORT': '3306', #你的数据库端口

    }

}

(3)、在mysql数据库中,创建数据库。

mysql> create database Django_ORM character set utf8;
Query OK, 1 row affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| abc                |
| crm                |
| django_orm         |
| mysql              |
| performance_schema |
| s1                 |
| sys                |
| t2                 |
+--------------------+
rows in set (0.00 sec)

mysql> use django_orm
Database changed

#####################################3
如果是连接linux系统上的mysql数据库,需要先授权,才能连接。
授权语句如下:

  grant all privileges on *.* to 'root'@'%' identified by '123456' with grant option;

  flush privileges;

(4)、在app01下面的models.py里面写建表语句

from django.db import models

"""
增:
models.UserGroup.objects.create(title='销售部'),创建列
删:
models.UserGroup.objects.filter(id=2).delete(),将id=2的那一行删除
改:
models.UserGroup.objects.filter(id=2).update(title='公关部'),将ID=2的那一列的内容改成公关部
查:
group_list = models.UserGroup.objects.all(),查看用户组的所有信息
group_list = models.UserGroup.objects.filter(id=1),查看用户组id=1的所有信息
group_list = models.UserGroup.objects.filter(id__gt=1),查看用户组的id>1的所有信息
group_list = models.UserGroup.objects.filter(id__lt=1),查看用户组的id<1的所有信息
"""

class Userinfo(models.Model):
    nid=models.BigAutoField(primary_key=True)
    username=models.CharField(max_length=32)
    password=models.CharField(max_length=64)

(5)、在终端执行命令

创建表

python manage.py makemigrations

写入数据库

python manage.py migrate
 
2、操作
(1)基本操作
from django.shortcuts import render,redirect,HttpResponse

from app01 import models
# ============关于数据库的相关操作==============
# 数据库的增、删、改、查
def ChangeSql(request):

    # 新增:
    # models.Userinfo.objects.create(username="hahaha",password="h123")
    # 查询:
    group_list=models.Userinfo.objects.all()
    # group_list=models.Userinfo.objects.filter(nid=2)
    # group_list=models.Userinfo.objects.filter(nid_gt=1)
    # group_list=models.Userinfo.objects.filter(nid_lt=1)
    # 改
    # models.Userinfo.objects.filter(nid=3).update(username="lailailai",password="la123")
    # 删除:
    models.Userinfo.objects.filter(nid=3).delete()

    print(group_list)
    for i in group_list:
        print(i.nid,i.username,i.password)
    return render(request,"ChangeSql.html",{"group_list":group_list})

(2)进阶操作 

# 获取个数
        #
        # models.Tb1.objects.filter(name='seven').count()
 
        # 大于,小于
        #
        # models.Tb1.objects.filter(id__gt=1)              # 获取id大于1的值
        # models.Tb1.objects.filter(id__gte=1)              # 获取id大于等于1的值
        # models.Tb1.objects.filter(id__lt=10)             # 获取id小于10的值
        # models.Tb1.objects.filter(id__lte=10)             # 获取id小于10的值
        # models.Tb1.objects.filter(id__lt=10, id__gt=1)   # 获取id大于1 且 小于10的值
 
        # in
        #
        # models.Tb1.objects.filter(id__in=[11, 22, 33])   # 获取id等于11、22、33的数据
        # models.Tb1.objects.exclude(id__in=[11, 22, 33])  # not in
 
        # isnull
        # Entry.objects.filter(pub_date__isnull=True)
 
        # contains
        #
        # models.Tb1.objects.filter(name__contains="ven")
        # models.Tb1.objects.filter(name__icontains="ven") # icontains大小写不敏感
        # models.Tb1.objects.exclude(name__icontains="ven")
 
        # range
        #
        # models.Tb1.objects.filter(id__range=[1, 2])   # 范围bettwen and
 
        # 其他类似
        #
        # startswith,istartswith, endswith, iendswith,
 
        # order by
        #
        # models.Tb1.objects.filter(name='seven').order_by('id')    # asc
        # models.Tb1.objects.filter(name='seven').order_by('-id')   # desc
 
        # group by
        #
        # from django.db.models import Count, Min, Max, Sum
        # models.Tb1.objects.filter(c1=1).values('id').annotate(c=Count('num'))
        # SELECT "app01_tb1"."id", COUNT("app01_tb1"."num") AS "c" FROM "app01_tb1" WHERE "app01_tb1"."c1" = 1 GROUP BY "app01_tb1"."id"
 
        # limit 、offset
        #
        # models.Tb1.objects.all()[10:20]
 
        # regex正则匹配,iregex 不区分大小写
        #
        # Entry.objects.get(title__regex=r'^(An?|The) +')
        # Entry.objects.get(title__iregex=r'^(an?|the) +')
 
        # date
        #
        # Entry.objects.filter(pub_date__date=datetime.date(2005, 1, 1))
        # Entry.objects.filter(pub_date__date__gt=datetime.date(2005, 1, 1))
 
        # year
        #
        # Entry.objects.filter(pub_date__year=2005)
        # Entry.objects.filter(pub_date__year__gte=2005)
 
        # month
        #
        # Entry.objects.filter(pub_date__month=12)
        # Entry.objects.filter(pub_date__month__gte=6)
 
        # day
        #
        # Entry.objects.filter(pub_date__day=3)
        # Entry.objects.filter(pub_date__day__gte=3)
 
        # week_day
        #
        # Entry.objects.filter(pub_date__week_day=2)
        # Entry.objects.filter(pub_date__week_day__gte=2)
 
        # hour
        #
        # Event.objects.filter(timestamp__hour=23)
        # Event.objects.filter(time__hour=5)
        # Event.objects.filter(timestamp__hour__gte=12)
 
        # minute
        #
        # Event.objects.filter(timestamp__minute=29)
        # Event.objects.filter(time__minute=46)
        # Event.objects.filter(timestamp__minute__gte=29)
 
        # second
        #
        # Event.objects.filter(timestamp__second=31)
        # Event.objects.filter(time__second=2)
        # Event.objects.filter(timestamp__second__gte=31)

(3)、高级操作

# ============其他的关于moders的应用=========================
#     排序
#     user_list=models.Userinfo.objects.all().order_by("id","username")#从小到大排序,当出现id一样的话,则按照名字排序
#     user_list2=models.Userinfo.objects.all().order_by("-id")#从大到小排序
#     print(user_list)
#     print(user_list2)
#     分组
    from django.db.models import Count,Sum,Min,Max
    # res=models.Userinfo.objects.values("ut_id").annotate(a=Count("id"))
    # print(res.query)#==>相当于SELECT `app01_userinfo`.`ut_id`, COUNT(`app01_userinfo`.`id`) AS `a` FROM `app01_userinfo` GROUP BY `app01_userinfo`.`ut_id`

    # res=models.Userinfo.objects.values("ut_id").annotate(b=Count("id")).filter(id__lt=2)
    # print(res)#==><QuerySet [{'ut_id': 1, 'b': 1}]>
    # print(res.query)#=>SELECT `app01_userinfo`.`ut_id`, COUNT(`app01_userinfo`.`id`) AS `b` FROM `app01_userinfo` WHERE `app01_userinfo`.`id` < 2 GROUP BY `app01_userinfo`.`ut_id` ORDER BY NULL
    # 过滤
    # res =models.Userinfo.objects.filter(id__lt=5)#小于
    # res =models.Userinfo.objects.filter(id__gt=5)#大于
    # res =models.Userinfo.objects.filter(id__lte=5)#小于等于
    # res =models.Userinfo.objects.filter(id__gte=5)#大于等于
    # res =models.Userinfo.objects.filter(id__in=[1,2,3])#id在列表中
    # res =models.Userinfo.objects.filter(id__range=[1,3])#id的范围属于1-3(包含1和3)
    # res=models.Userinfo.objects.filter(username__startswith="ha")
    # res=models.Userinfo.objects.filter(username__endswith="ha")
    # res=models.Userinfo.objects.filter(username__contains="xu")#包含
    # res=models.Userinfo.objects.exclude(id=1)#排除id=1的
    # print(res)

# ======关于F、Q、extra
#     F:
    from django.db.models import F
    #将数据库中的年级那一列都自加一
    # models.Userinfo.objects.all().update(age=F("age")+1)

    # Q:
    # res=models.Userinfo.objects.filter(id=1,username="xuyuanyuan")#里面是and的关系
    # print(res)#==><QuerySet []>
    # dict={
    #     "id":1,
    #     "username":"xuyuanyuan"
    # }#里面是and的关系
    # ret=models.Userinfo.objects.filter(**dict)
    # print(ret)#===><QuerySet []>

    from django.db.models import Q
    # Q使用有两种方式:对象方式,方法方式 *
    # res=models.Userinfo.objects.filter(Q(id__lt=5))
    # res=models.Userinfo.objects.filter(Q(id__lt=5)|Q(id__gt=315))#或
    # res=models.Userinfo.objects.filter(Q(id__lt=5)&Q(id__gt=310))
    # print(res)

    # q1=Q()
    # q1.connector="OR"
    # q1.children.append(("id__gte",1))
    # q1.children.append(("id",3))
    # q1.children.append(("id",4))
    #
    # q2 = Q()
    # q2.connector = 'OR'
    # q2.children.append(('id', 11))
    # q2.children.append(('id', 1))
    # q2.children.append(('id', 10))
    #
    # q3 = Q()
    # q3.connector = 'AND'
    # q3.children.append(('id', 111))
    # q3.children.append(('id', 200))
    # q2.add(q3,'OR')
    #
    # con = Q()
    # con.add(q1, 'AND')
    # con.add(q2, 'AND')
    # res=models.Userinfo.objects.filter(con)
    # print(res)#===><QuerySet [<Userinfo: 1-hahaha-19>]>
    # print(res.query)#==>上面定义的就相当于下面的sql语句:
    # SELECT `app01_userinfo`.`id`,
    #  `app01_userinfo`.`username`,
    # `app01_userinfo`.`age`,
    # `app01_userinfo`.`ut_id`
    # FROM `app01_userinfo`
    # WHERE ((`app01_userinfo`.`id` >= 1 OR `app01_userinfo`.`id` = 3 OR `app01_userinfo`.`id` = 4)
    # AND (`app01_userinfo`.`id` = 11 OR `app01_userinfo`.`id` = 1 OR `app01_userinfo`.`id` = 10
    # OR (`app01_userinfo`.`id` = 111 AND `app01_userinfo`.`id` = 200)))



    # condition_dict = {
    #     'k1':[1,2,3,4],
    #     'k2':[1,2,10,11],
    #     "k3":[1,2,100,111,200],
    # }
    # con = Q()
    # for k,v in condition_dict.items():
    #     q = Q()
    #     q.connector = 'OR'
    #     for i in v:
    #         q.children.append(('id', i))
    #     con.add(q,'AND')
    # res=models.Userinfo.objects.filter(con)
    # print(res)
    # print(res.query)


    # extra:额外的
    #
    # extra(self, select=None, where=None, params=None, tables=None, order_by=None, select_params=None)
    #    Entry.objects.extra(select={'new_id': "select col from sometable where othercol > %s"}, select_params=(1,))
    #    Entry.objects.extra(where=['headline=%s'], params=['Lennon'])
    #    Entry.objects.extra(where=["foo='a' OR bar = 'a'", "baz = 'a'"])
    #    Entry.objects.extra(select={'new_id': "select id from tb where id > %s"}, select_params=(1,), order_by=['-nid'])
    
#原生sql
    # name_map = {'title': 'titles'}
    # v1 = models.Userinfo.objects.raw('SELECT id,title FROM app01_usertype',translations=name_map)
    # print(v1.query)
    # print(v1)
    # for i in v1:
    #     print(i,type(i))

其它

  

(4)、其他操作

from django.shortcuts import render,redirect,HttpResponse

from app01 import models
def all(self)
    # 获取所有的数据对象
 
def filter(self, *args, **kwargs)
    # 条件查询
    # 条件可以是:参数,字典,Q
 
def exclude(self, *args, **kwargs)
    # 条件查询
    # 条件可以是:参数,字典,Q
 
def select_related(self, *fields)
     性能相关:表之间进行join连表操作,一次性获取关联的数据。
     model.tb.objects.all().select_related()
     model.tb.objects.all().select_related('外键字段')
     model.tb.objects.all().select_related('外键字段__外键字段')
 
def prefetch_related(self, *lookups)
    性能相关:多表连表操作时速度会慢,使用其执行多次SQL查询在Python代码中实现连表操作。
            # 获取所有用户表
            # 获取用户类型表where id in (用户表中的查到的所有用户ID)
            models.UserInfo.objects.prefetch_related('外键字段')
 
 
 
            from django.db.models import Count, Case, When, IntegerField
            Article.objects.annotate(
                numviews=Count(Case(
                    When(readership__what_time__lt=treshold, then=1),
                    output_field=CharField(),
                ))
            )
 
            students = Student.objects.all().annotate(num_excused_absences=models.Sum(
                models.Case(
                    models.When(absence__type='Excused', then=1),
                default=0,
                output_field=models.IntegerField()
            )))
 
def annotate(self, *args, **kwargs)
    # 用于实现聚合group by查询
 
    from django.db.models import Count, Avg, Max, Min, Sum
 
    v = models.UserInfo.objects.values('u_id').annotate(uid=Count('u_id'))
    # SELECT u_id, COUNT(ui) AS `uid` FROM UserInfo GROUP BY u_id
 
    v = models.UserInfo.objects.values('u_id').annotate(uid=Count('u_id')).filter(uid__gt=1)
    # SELECT u_id, COUNT(ui_id) AS `uid` FROM UserInfo GROUP BY u_id having count(u_id) > 1
 
    v = models.UserInfo.objects.values('u_id').annotate(uid=Count('u_id',distinct=True)).filter(uid__gt=1)
    # SELECT u_id, COUNT( DISTINCT ui_id) AS `uid` FROM UserInfo GROUP BY u_id having count(u_id) > 1
 
def distinct(self, *field_names)
    # 用于distinct去重
    models.UserInfo.objects.values('nid').distinct()
    # select distinct nid from userinfo
 
    注:只有在PostgreSQL中才能使用distinct进行去重
 
def order_by(self, *field_names)
    # 用于排序
    models.UserInfo.objects.all().order_by('-id','age')
 
def extra(self, select=None, where=None, params=None, tables=None, order_by=None, select_params=None)
    # 构造额外的查询条件或者映射,如:子查询
 
    Entry.objects.extra(select={'new_id': "select col from sometable where othercol > %s"}, select_params=(1,))
    Entry.objects.extra(where=['headline=%s'], params=['Lennon'])
    Entry.objects.extra(where=["foo='a' OR bar = 'a'", "baz = 'a'"])
    Entry.objects.extra(select={'new_id': "select id from tb where id > %s"}, select_params=(1,), order_by=['-nid'])
 
 def reverse(self):
    # 倒序
    models.UserInfo.objects.all().order_by('-nid').reverse()
    # 注:如果存在order_by,reverse则是倒序,如果多个排序则一一倒序
 
 
 def defer(self, *fields):
    models.UserInfo.objects.defer('username','id')
    或
    models.UserInfo.objects.filter(...).defer('username','id')
    #映射中排除某列数据
 
 def only(self, *fields):
    #仅取某个表中的数据
     models.UserInfo.objects.only('username','id')
     或
     models.UserInfo.objects.filter(...).only('username','id')
 
 def using(self, alias):
     指定使用的数据库,参数为别名(setting中的设置)
 
 
##################################################
# PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS #
##################################################
 
def raw(self, raw_query, params=None, translations=None, using=None):
    # 执行原生SQL
    models.UserInfo.objects.raw('select * from userinfo')
 
    # 如果SQL是其他表时,必须将名字设置为当前UserInfo对象的主键列名
    models.UserInfo.objects.raw('select id as nid from 其他表')
 
    # 为原生SQL设置参数
    models.UserInfo.objects.raw('select id as nid from userinfo where nid>%s', params=[12,])
 
    # 将获取的到列名转换为指定列名
    name_map = {'first': 'first_name', 'last': 'last_name', 'bd': 'birth_date', 'pk': 'id'}
    Person.objects.raw('SELECT * FROM some_other_table', translations=name_map)
 
    # 指定数据库
    models.UserInfo.objects.raw('select * from userinfo', using="default")
 
    ################### 原生SQL ###################
    from django.db import connection, connections
    cursor = connection.cursor()  # cursor = connections['default'].cursor()
    cursor.execute("""SELECT * from auth_user where id = %s""", [1])
    row = cursor.fetchone() # fetchall()/fetchmany(..)
 
 
def values(self, *fields):
    # 获取每行数据为字典格式
 
def values_list(self, *fields, **kwargs):
    # 获取每行数据为元祖
 
def dates(self, field_name, kind, order='ASC'):
    # 根据时间进行某一部分进行去重查找并截取指定内容
    # kind只能是:"year"(年), "month"(年-月), "day"(年-月-日)
    # order只能是:"ASC"  "DESC"
    # 并获取转换后的时间
        - year : 年-01-01
        - month: 年-月-01
        - day  : 年-月-日
 
    models.DatePlus.objects.dates('ctime','day','DESC')
 
def datetimes(self, field_name, kind, order='ASC', tzinfo=None):
    # 根据时间进行某一部分进行去重查找并截取指定内容,将时间转换为指定时区时间
    # kind只能是 "year", "month", "day", "hour", "minute", "second"
    # order只能是:"ASC"  "DESC"
    # tzinfo时区对象
    models.DDD.objects.datetimes('ctime','hour',tzinfo=pytz.UTC)
    models.DDD.objects.datetimes('ctime','hour',tzinfo=pytz.timezone('Asia/Shanghai'))
 
    """
    pip3 install pytz
    import pytz
    pytz.all_timezones
    pytz.timezone(‘Asia/Shanghai’)
    """
 
def none(self):
    # 空QuerySet对象
 
 
####################################
# METHODS THAT DO DATABASE QUERIES #
####################################
 
def aggregate(self, *args, **kwargs):
   # 聚合函数,获取字典类型聚合结果
   from django.db.models import Count, Avg, Max, Min, Sum
   result = models.UserInfo.objects.aggregate(k=Count('u_id', distinct=True), n=Count('nid'))
   ===> {'k': 3, 'n': 4}
 
def count(self):
   # 获取个数
 
def get(self, *args, **kwargs):
   # 获取单个对象
 
def create(self, **kwargs):
   # 创建对象
 
def bulk_create(self, objs, batch_size=None):
    # 批量插入
    # batch_size表示一次插入的个数
    objs = [
        models.DDD(name='r11'),
        models.DDD(name='r22')
    ]
    models.DDD.objects.bulk_create(objs, 10)
 
def get_or_create(self, defaults=None, **kwargs):
    # 如果存在,则获取,否则,创建
    # defaults 指定创建时,其他字段的值
    obj, created = models.UserInfo.objects.get_or_create(username='root1', defaults={'email': '1111111','u_id': 2, 't_id': 2})
 
def update_or_create(self, defaults=None, **kwargs):
    # 如果存在,则更新,否则,创建
    # defaults 指定创建时或更新时的其他字段
    obj, created = models.UserInfo.objects.update_or_create(username='root1', defaults={'email': '1111111','u_id': 2, 't_id': 1})
 
def first(self):
   # 获取第一个
 
def last(self):
   # 获取最后一个
 
def in_bulk(self, id_list=None):
   # 根据主键ID进行查找
   id_list = [11,21,31]
   models.DDD.objects.in_bulk(id_list)
 
def delete(self):
   # 删除
 
def update(self, **kwargs):
    # 更新
 
def exists(self):
   # 是否有结果
View Code

 

重点:连表操作(正反)

(5)、一对一和一对多正反操作

a、正向和反向操作

.all()=====》查看到的数据类型都是Queryset类型,类似于列表,里面都是一个个对象

.values()===》使用.values查看数据,所查看的数据是Queryset里面套的字典,

.values_list()===》使用.values_list的方法查看的话,所查看的数据是列表里面套字典的方式

示例:

model.py

from django.db import models

from django.views import View

"""
增:
models.UserGroup.objects.create(title='销售部'),创建列
删:
models.UserGroup.objects.filter(id=2).delete(),将id=2的那一行删除
改:
models.UserGroup.objects.filter(id=2).update(title='公关部'),将ID=2的那一列的内容改成公关部
查:
group_list = models.UserGroup.objects.all(),查看用户组的所有信息
group_list = models.UserGroup.objects.filter(id=1),查看用户组id=1的所有信息
group_list = models.UserGroup.objects.filter(id__gt=1),查看用户组的id>1的所有信息
group_list = models.UserGroup.objects.filter(id__lt=1),查看用户组的id<1的所有信息
"""

class UserType(models.Model):
    # 用户类型
    title=models.CharField(max_length=32)
class Userinfo(models.Model):
    # 用户表
    # nid=models.BigAutoField(primary_key=True)
    username=models.CharField(max_length=32)
    age=models.IntegerField()
    ut=models.ForeignKey("UserType")
    def __str__(self):
        return "%s-%s" %(self.id,self.username)

views.py

from django.shortcuts import render,HttpResponse
from django.views import View
from app01 import models
 # 关于查看和获取数据(正向操作和反向操作)

# 1.models.Userinfo.objects.all()查看到的数据类型都是Queryset类型,类似于列表,里面都是一个个对象
    # Queryset[obj,obj,obj,]
    # res=models.Userinfo.objects.all()
    # # print(res)
    # for obj in res:
    #     print(obj.username,obj.age,obj.ut_id,obj.ut.title)

#(1)一个用户对应一个用户类型
    #  UserInfo,ut是外键字段,可以通过点的方式连表 - 正向操作
    # PS: 一个用户只有一个用户类型
    # Queryset[obj,obj,obj,]

    # res=models.Userinfo.objects.all().first()
    # print(res.username, res.age, res.ut_id, res.ut.title)


#(2)一个用户类型可以对应多个用户(将同一类型下的用户全部取出)
    # UserType, 表名小写_set.all()  - 反向操作
    # PS: 一个用户类型下可以有很多用户

    # obj = models.UserType.objects.all().first()
    # print(obj)   #=====>UserType object
    # print(obj.userinfo_set.all())#====><QuerySet [<Userinfo: Userinfo object>, <Userinfo: Userinfo object>]>
    # print('用户类型',obj.id,obj.title)#===>用户类型 1 普通用户
    # for row in obj.userinfo_set.all():
    #     print(row.username,row.age)

    # result = models.UserType.objects.all()
    # for item in result:
    #     print(item.title,item.userinfo_set.filter(username='hahaha'))

# 2.使用.values查看数据,所查看的数据是Queryset里面套的字典,
#     无法向上面的1一样进行obj.取值
#     result=models.Userinfo.objects.all().values()
#     print(result)#===>
#     """
#     < QuerySet[{'id': 1, 'username': 'hahaha', 'age': 18, 'ut_id': 1},
#      {'id': 2, 'username': 'xuyuanyuan', 'age': 18,'ut_id': 3}                                                                                                           'ut_id': 1}] >
#     """
#     for i in result:
#         print(i)#===>{'id': 1, 'username': 'hahaha', 'age': 18, 'ut_id': 1}

# 3.使用.values_list的方法查看的话,所查看的数据是列表里面套字典的方式
#     result=models.Userinfo.objects.all().values_list("username","age")
#     print(result)
#     """
#     < QuerySet[('hahaha', 18),
#                ('xuyuanyuan', 18),
#                ('leileilei', 10),
#                ('kkkkk', 18),
#                ('bob', 18),
#                ('rose', 18),
#                ('jack', 18),
#                ('nack', 18)] >
#                """
#     for i in result:
#         print(i)
#return HttpResponse("hello")

 

b、多对多连表(正向和反向操作)

.all()=====》查看到的数据类型都是Queryset类型,类似于列表,里面都是一个个对象

.values()===》使用.values查看数据,所查看的数据是Queryset里面套的字典,

.values_list()===》使用.values_list的方法查看的话,所查看的数据是列表里面套字典的方式

from django.shortcuts import render,HttpResponse
from django.views import View
from app01 import models
from django.core.paginator import 

def test(request):

# 当数据获取多个数据时,分别用上述1.2.3来实现正反向连表操作:
#     1.
    # (1)正向操作=====>根据userinfo来查询操作
    # [obj,obj,obj]正向操作:
#     models.Userinfo.objects.all()
#     models.Userinfo.objects.filter(ut_id__gt=2)
#     res=models.Userinfo.objects.filter(ut_id__gt=2)
#     for i in res:
#         print(i.username,i.age,i.ut.title)
    #(2)一个用户类型可以对应多个用户(将同一类型下的用户全部取出)
    # UserType, 表名小写_set.all()  - 反向操作
    # PS: 一个用户类型下可以有很多用户

    # obj = models.UserType.objects.all().first()
    # print(obj)   #=====>UserType object
    # print(obj.userinfo_set.all())#====><QuerySet [<Userinfo: Userinfo object>, <Userinfo: Userinfo object>]>
    # print('用户类型',obj.id,obj.title)#===>用户类型 1 普通用户
    # for row in obj.userinfo_set.all():
    #     print(row.username,row.age)

    # result = models.UserType.objects.all()
    # for item in result:
    #     print(item.title,item.userinfo_set.filter(username='hahaha'))


    # 2.[{"id":1,"username":"xuyuanyuan"}]
    # (1)正向操作:====>根据userinfo来操作
    # models.Userinfo.objects.all().values("username","age")
    # models.Userinfo.objects.filter(id__gt=2).values("username","age")
    # res=models.Userinfo.objects.filter(id__gt=7).values("username","age")
    # # 根据字典的key取值,无法连表,无法跨表去取usertype的title值
    # for i in res:
    #     print(i["username"],i["age"])  #===>nack 18

    #解决办法: 但是如果一开始取值的时候连表的话,则for循环可以取得连表后的值
    # res=models.Userinfo.objects.all().values("username", "age","ut__title")
    # for i in res:
    #     print(i["username"],i["age"],i["ut__title"])

    # (2)反向操作====>根据usertype来操作:
    # models.UserType.objects.all().values("id","title")
    # models.UserType.objects.filter(id__1t=4).values("id","title")
    # res=models.UserType.objects.filter(id__1t=4).values("id","title")
    # 根据字典的key取值,无法连表,无法跨表去取userinfo的值

    # 解决办法: 但是如果一开始取值的时候连表的话,则for循环可以取得连表后的值
    # res1=models.UserType.objects.filter(id=1).values("id","title","userinfo")
    # res2=models.UserType.objects.filter(id=1).values("id","title","userinfo__username")
    # res3=models.UserType.objects.filter(id=1).values("id","title","userinfo__age")
    # print(res1)
    # print(res2)
    # print(res3)



    # 3.[("xuyuanyuan",18),("kkkk",18)]
    # (1)正向操作:====>根据userinfo来操作
    # models.Userinfo.objects.all().values_list()
    # models.Userinfo.objects.filter(ut_id__gt=2).values_list()
    # res=models.Userinfo.objects.filter(ut_id__gt=2).values_list()
    # 根据元祖的索引取值,无法实现连表,无法获取usertype内的信息
    # for i in res:
    #     print(i[0],i[1],i[2])

    # 解决办法:一开始查询的时候就连表,则for循环即可取值
    # models.Userinfo.objects.all().values_list("username","age","ut__title")
    # res=models.Userinfo.objects.filter(ut_id__gt=3).values_list("username","age","ut__title")
    # for i in res:
    #     print(i[0],i[2])#===>kkkkk 牛逼用户


    # (2)反向操作====>根据usertype来操作:
    # models.UserType.objects.all().values_list("id","title")
    # 根据字典的key取值,无法连表,无法跨表去取userinfo的值

    # 解决办法: 但是如果一开始取值的时候连表的话,则for循环可以取得连表后的值
    # res1 = models.UserType.objects.filter(id=1).values_list("id", "title", "userinfo")
    # res2 = models.UserType.objects.filter(id=1).values_list("id", "title", "userinfo__username")
    # res3 = models.UserType.objects.filter(id=1).values_list("id", "title", "userinfo__age")
    # print(res1)#===><QuerySet [(1, '普通用户', 1), (1, '普通用户', 8)]>
    # print(res2)#===><QuerySet [(1, '普通用户', 'hahaha'), (1, '普通用户', 'nack')]>
    # print(res3)#===><QuerySet [(1, '普通用户', 18), (1, '普通用户', 18)]>

    # return render(request,"test.html")

  

 

posted @ 2017-07-02 23:32  白木潇潇夕  阅读(179)  评论(0编辑  收藏  举报