Django配置数据库utf-8编码
- settings.py文件中配置数据库
DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', 'NAME': 'dj2022', 'HOST': '127.0.0.1', 'PORT': 3306, 'USER': 'root', 'PASSWORD': '1064865165QAF', 'TEST': { 'CHARSET': 'utf-8', 'COLLATION': 'utf-8_general_ci' } } } SESSION_ENGINE = 'django.contrib.sessions.backends.db'
2.在Navicat中输入如下命令
CREATE DATABASE 数据库名 DEFAULT SET utf8;
一、日期查询
添加日期字段：
DateTimeField(verbose_name=‘’, auto_now=True)
auto_now 表示以现在的时间作为其值
日期字段的添加
- 创建一个模型类
2、进行数据库的迁移后，在终端中进入shell环境，添加字段值
3、在Navicat中进行数据的添加
日期字段的查询
1、查询生日为1993-12-14
>>> Husband_1.objects.filter(birthday='1993-12-14') <QuerySet [<Husband_1: Husband_1 object (1)>]>
2、查询1991年后的数据
>>> Husband_1.objects.filter(birthday__gt='1991-01-01') <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (3)>, <Husband_1: Husband_1 object (4)>, <Husband_1: Husband_1 object (5)>]>
3、只根据年代或月份查询
>>> Husband_1.objects.filter(birthday__year__gt='1991') <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (3)>, <Husband_1: Husband_1 object (4)>, <Husband_1: Husband_1 object (5)>]>
>>> Husband_1.objects.filter(birthday__month__gt='8') <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (3)>, <Husband_1: Husband_1 object (4)>]>
二、F、Q对象
F对象
F对象，用于属性与属性之间进行比较
导包：from django.db.models import F
语法：filter(字段名_运算符=F(‘字段名’))
- 例：查询身高大体重两倍的数据
>>> from django.db.models import F >>> Husband_1.objects.filter(weight__lt=F('height')/2) <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (2)>, <Husband_1: Husband_1 object (3)>, <Husband_1: Husband_1 object (4)>]>
Q对象
Q对象，用于逻辑运算操作，与、或、非
导包：from django.db.models import Q
- 例1：查询大于1993年或小于1992年的数据
>>> Husband_1.objects.filter(Q(birthday__year__gt='1993')|Q(birthday__year__lt='1992')) <QuerySet [<Husband_1: Husband_1 object (2)>, <Husband_1: Husband_1 object (3)>]>
2. 查询除了1993年的所有数据
>>> Husband_1.objects.filter(~Q(birthday__year__gt='1993')) <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (2)>, <Husband_1: Husband_1 object (4)>, <Husband_1: Husband_1 object (5)>]>
3. 查询大于1992年且年龄为33的数据
>>> Husband_1.objects.filter(Q(birthday__year__gt='1992')&Q(age=33)) <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (5)>]>
或
>>> Husband_1.objects.filter(Q(birthday__year__gt='1992',age=33)) <QuerySet [<Husband_1: Husband_1 object (1)>, <Husband_1: Husband_1 object (5)>]>
三、关联查询
一对一关系
1.添加模型类
class Wife_1(models.Model): name = models.CharField(verbose_name='姓名', max_length=8) age = models.IntegerField(verbose_name='年龄') height = models.FloatField(verbose_name='身高') weight = models.FloatField(verbose_name='体重', null=None) husband = models.OneToOneField(Husband_1, verbose_name='丈夫', on_delete=models.CASCADE) class Meta: db_table = 'Wife_1'
models.OneToOneField(Husband_1, verbose_name=‘丈夫’, on_delete=models.CASCADE) on_delete，设置表与表之间的级联
级联：将表与表之间进行联系，当主表中的数据删除时，子表中的数据也会被删除，在进行一对一的关联时，必须添加上on_delete参数
- 级联演示
绑定表husband_1中id为3的数据
>>> Wife_1.objects.create(name='小芳', age=30, height=168, weight=48, husband_id=3) <Wife_1: Wife_1 object (1)>
>>> wife = Wife_1.objects.get(id=1) >>> husband = Husband_1.objects.get(id=3) >>> wife.husband <Husband_1: Husband_1 object (3)> >>> wife.husband.name '王五'
从主表中查询子表的数据：
例如：husband.子表的模型类类名（小写）.name
>>>husband.wife_1.name '小芳'
一对多多对一
- 添加模型类
class Children_1(models.Model): Children_choice = ( (1, '男'), (2, '女') ) name = models.CharField(verbose_name='姓名', max_length=8) age = models.IntegerField(verbose_name='年龄') sex = models.CharField(choices=Children_choice, verbose_name='性别', max_length=2) father = models.ForeignKey(Husband_1, on_delete=models.CASCADE) mother = models.ForeignKey(Wife_1, on_delete=models.CASCADE) class Meta: db_table = 'Children_1'
2.建立连接
>>> Children_1.objects.create(name='王小五', age=10, sex='男', father_id=3, mother_id=1) <Children_1: Children_1 object (1)> >>> Children_1.objects.create(name='王小美', age=8, sex=2, father_id=3, mother_id=1) <Children_1: Children_1 object (2)>
3.查询演示
>>> son = Children_1.objects.get(id=1) >>> daughter = Children_1.objects.get(id=2) >>> son.mother <Wife_1: Wife_1 object (1)> >>> daughter.father.name '王五'
- 使用_set进行一对多的查询
没有related_name参数时，从‘一‘（父母）这一方查询’多‘（孩子）的一方，需要在模型类类名小写后加上’_set‘进行查询，当查询的记过可能有多个的时候，就需要再模型类类名小写后加上’_set’进行查询
>>> mother = Wife_1.objects.get(id=1) >>> mother.children_1.set >>> mother.children_1_set <django.db.models.fields.related_descriptors.create_reverse_many_to_one_manager.<locals>.RelatedManager object at 0x0000026FE5696988> >>> mother.children_1_set.all() <QuerySet [<Children_1: Children_1 object (1)>, <Children_1: Children_1 object (2)>]> >>> data1 = mother.children_1_set.all() >>> data1[0].name '王小五'
- 使用related_name参数
related_name参数：表示为关联的字段起一个关联名称，相当于起别名，便于开发人员进行查询
>>> wife = Wife_1.objects.get(id=1) >>> wife.mother <django.db.models.fields.related_descriptors.create_reverse_many_to_one_manager.<locals>.RelatedManager object at 0x00000272C5CD68C8> >>> data = wife.mother.all() # 获取所有孩子的信息 >>> data <QuerySet [<Children_1: Children_1 object (1)>, <Children_1: Children_1 object (2)>]> >>> data[1].name '王小美' >>> data[0].name '王小五'
多对多查询
- 添加模型类
class Brother_1(models.Model): Brother_choice = ( (1, '男'), (2, '女') ) name = models.CharField(verbose_name='姓名', max_length=8) age = models.IntegerField(verbose_name='年龄') sex = models.CharField(choices=Brother_choice, verbose_name='性别', max_length=2) brother = models.ManyToManyField(Husband_1, verbose_name='兄弟') sister = models.ManyToManyField(Wife_1, verbose_name='姐妹') class Meta: db_table = 'brother_1'
数据库表的命名格式：模型类名小写_关联字段名 -> brother_1_brother
2.演示如下
>>> Brother_1.objects.create(name='大海', age=35, sex='男') <Brother_1: Brother_1 object (1)> >>> brother = Brother_1.objects.get(id=1) >>> husband = Husband_1.objects.get(id=1) # 1、通过对象进行关联 >>> brother.brother.set([husband,]) # 2、通过id进行关联
