Djiango 连接数据库mysql 的基本数据操作

1、单表操作

(1) .增加操作

 1 # 增加操作
 2 def add_person(request):
 3     # 1.使用save() 方法
 4     # person_obj = models.Person()
 5     # person_obj.name = 'wanwu'
 6     # person_obj.age = 18
 7     # person_obj.gender = False
 8     # person_obj.address = 'shanghai'
 9     # person_obj.save()
10     # 2.使用create() 方法
11     # person_obj = models.Person.objects.create(name='lsi', age=20, gender=True, address='shenzhen')
12     # print(person_obj.id)
13
14     models.Goods.objects.create(name='苹果', xl=1000, kc=2000)
15     models.Goods.objects.create(name='香蕉', xl=1000, kc=500)
16     models.Goods.objects.create(name='梨', xl=1000, kc=700)

(2) .查询操作

 1 def find_person(request):
 2     # 1.get() 返回值是一个具体对象。如果不存在则报错！！！,返回多了也报错
 3     # person_obj = models.Person.objects.get(id=2)
 4     # print(person_obj)
 5
 6     # 2.first() 和last()方法 返回值是一个具体的对象。
 7     # ret = models.Person.objects.last()
 8     # print(ret)
 9     # 3.all() 返回一个QuerySet对象，类似于列表。
10     # person_obj_list = models.Person.objects.all()
11     # print(person_obj_list)
12     # # <QuerySet [<Person: Person object (1)>, <Person: Person object (2)>, <Person: Person object (3)>]>
13     # for person_obj in person_obj_list:
14     #     print(person_obj.name)
15     # 4.filter()
16     # person_obj_list = models.Person.objects.filter(age=18)
17     # print(person_obj_list)  # <QuerySet [<Person: Person object (1)>, <Person: Person object (3)>]>
18     # 多个条件之间使用并且的关系。
19     # ret = models.Person.objects.filter(age=18, name='zss')
20     # print(ret)
21     # 5.排序order_by() -id 表示降序。
22     # ret = models.Person.objects.all().order_by('-id')
23     # print(ret)
24
25     # 6.双下划线查询
26     # ret = models.Person.objects.filter(age__gte=18)
27     # print(ret)
28     # ret = models.Person.objects.filter(name__startswith='z')
29     # print(ret)
30
31     # 7.聚合函数aggregate()
32     from django.db.models import Count, Max, Min, Sum, Avg, F, Q
33     # 求年龄的平均值
34     # ret = models.Person.objects.all().aggregate(Avg('age'))
35     # print(ret)  # {'age__avg': 18.6667}
36
37     # 8.分组 annotate()
38     # 按性别来分组，求人数
39     # ret = models.Person.objects.all().values('gender').annotate(Count('gender'))
40     # print(ret)
41     # 9. F和Q查询
42     # F 查询：同一个模型类中，不同属性进行比较。
43     # 查询销量(xl)大于库存(kc)的商品
44     # ret = models.Goods.objects.filter(xl__gt=F('kc'))
45     # print(ret)
46     # Q查询：可以实现复杂的查询 not (~)、and (&)、or (|) 关系的使用。
47     # 查询库存大于1000 、或者销量等1000的商品
48     # ret = models.Goods.objects.filter(Q(xl=1000) | Q(kc__gt=1000))
49     # print(ret)
50     # ret = models.Goods.objects.all()[2]  # 索引
51     # print(ret)
52     # ret = models.Goods.objects.all()[1:]  # 切片
53     # print(ret)
54     return HttpResponse('find person...')

(3) .修改操作

 1 def update_person(request):
 2     # 1.使用save()
 3     # person_obj = models.Person.objects.get(id=2)
 4     # person_obj.age = 23
 5     # person_obj.save()
 6     # 2. 使用update()方法，查询出多个来统一修改
 7     ret = models.Person.objects.filter(name='lsi').update(age=22)
 8     print(ret)
 9
10     return HttpResponse('update person...')

(4) .删除操作

# 删除操作
def delete_person(request):
    person_obj = models.Person.objects.get(id=1)
    person_obj.delete()

    return HttpResponse('delete person...')

2、一对一操作

(1) .模型类

 1 class User(models.Model):
 2     id = models.AutoField(primary_key=True)
 3     name = models.CharField(max_length=32)
 4     age = models.IntegerField(default=10)
 5
 6
 7 class IdCard(models.Model):
 8     id = models.AutoField(primary_key=True)
 9     address = models.TextField(default='beijing')
10     cardnum = models.CharField(max_length=32)  # 身份证号
11     # 一对一关联
12     # to=User :关联的表。on_delete:删除策略。
13     # models.CASCADE：级联删除，删除一的一方的时候，另外一方也删除。
14     # related_name='card':表示反向查询的时候使用属性。如果不写，反向查询的时候默认值为类名小写idcard
15     user = models.OneToOneField(to=User, on_delete=models.CASCADE, related_name='card')  # 在数据库中会自动添加_id
16
17
18
19
20
21
22
23 def one_add(request):
24     # user_obj = models.User()
25     # user_obj.name = 'zs'
26     # user_obj.age = 18
27     # user_obj.save()
28     # idcard_obj = models.IdCard()
29     # idcard_obj.cardnum = '131126333'
30     # idcard_obj.address = 'beijing'
31     # idcard_obj.user = user_obj  # 设置关系--> 赋值对象
32     # idcard_obj.save()
33
34     user_obj = models.User()
35     user_obj.name = 'lsi'
36     user_obj.age = 20
37     user_obj.save()
38
39     idcard_obj = models.IdCard()
40     idcard_obj.cardnum = '131126444'
41     idcard_obj.address = 'shangai'
42     idcard_obj.user_id = user_obj.id  # 设置关系--> 赋值id
43     idcard_obj.save()
44
45     return HttpResponse('one add...')
46
47
48 # 查询
49
50 def one_find(request):
51     # 正向查询
52     # 1.查询id 为1 的身份证对应的人。
53     # card_obj = models.IdCard.objects.get(id=1)
54     # user_obj = card_obj.user  # 通过关系属性获取对象
55     # print(user_obj, user_obj.name)  # User object (1)
56
57     # 反向查询
58     # 2.查询zs 对应的身份证对象
59     user_obj = models.User.objects.filter(name='zs').first()
60     # card_obj = user_obj.idcard  # 类名小写，直接获取到对象。
61     card_obj = user_obj.card  # 使用的related_name属性的值。
62     print(card_obj)
63     return HttpResponse('one find...')
64
65
66 def one_delete(request):
67     # 删除zs
68     user_obj = models.User.objects.get(id=1)
69     user_obj.delete()  # 级联删除身份证
70     return HttpResponse('one delete...')

3、一对多操作

 1 # 部门表
 2 class Dept(models.Model):
 3     id = models.AutoField(primary_key=True)
 4     name = models.CharField(max_length=32)
 5
 6
 7 class Employee(models.Model):
 8     id = models.AutoField(primary_key=True)
 9     name = models.CharField(max_length=32)
10     # 设置外键
11     dpet = models.ForeignKey(to=Dept, on_delete=models.CASCADE, related_name='emps')
12
13
14
15
16
17 # 一对多操作
18
19 def onetomany_add(request):
20     dept_obj = models.Dept.objects.create(name='市场部')
21     emp_obj = models.Employee()
22     emp_obj.name = 'lsi'
23     emp_obj.dpet = dept_obj  # 赋值对象即可
24     emp_obj.save()
25
26     emp_obj1 = models.Employee()
27     emp_obj1.name = 'ww'
28     emp_obj1.dpet = dept_obj
29     emp_obj1.save()
30
31     emp_obj2 = models.Employee()
32     emp_obj2.name = 'zl'
33     emp_obj2.dpet = dept_obj
34     emp_obj2.save()
35
36     return HttpResponse('onetomany_add...')
37
38
39 # 查询
40
41 def onetomany_find(request):
42     # 正向查询
43     # 1.查询lsi 对应的部门
44     # emp_obj = models.Employee.objects.filter(name='lsi').first()
45     # print(emp_obj.dpet)  # 获取部门对象
46
47     # 反向查询
48     # 2.查询市场部对应的所有员工
49     dept_obj = models.Dept.objects.get(name='市场部')
50     # ret = dept_obj.employee_set.all()  # 使用类名小写_set.方法()
51     ret = dept_obj.emps.all()  # 设置查询名称
52     print(ret)
53
54     return HttpResponse('onetomany_find...')
55
56
57 # 删除
58 def onetomany_delete(request):
59     # 1.删除lsi
60     # emp_obj = models.Employee.objects.filter(name='lsi').first()
61     # emp_obj.delete()
62
63     # 2.删除市场部,会级联删除对应的员工。
64     dept_obj = models.Dept.objects.get(name='市场部')
65     dept_obj.delete()
66
67     return HttpResponse('onetomany_delete...')

4、多对多操作

 1 class Teacher(models.Model):
 2     id = models.AutoField(primary_key=True)
 3     name = models.CharField(max_length=32)
 4     salary = models.IntegerField(default=1000)
 5
 6
 7 class Student(models.Model):
 8     id = models.AutoField(primary_key=True)
 9     name = models.CharField(max_length=32)
10     age = models.IntegerField(default=20)
11     # 多对多关系
12     teachers = models.ManyToManyField(to=Teacher)
13
14
15
16
17
18 def many_add(request):
19     std_obj1 = models.Student()
20     std_obj1.name = 'zs'
21     std_obj1.age = 10
22     std_obj1.save()
23     std_obj2 = models.Student()
24     std_obj2.name = 'sli'
25     std_obj2.save()
26
27     tea_obj = models.Teacher()
28     tea_obj.name = 'laowang'
29     tea_obj.save()
30
31     tea_obj1 = models.Teacher()
32     tea_obj1.name = 'laoli'
33     tea_obj1.save()
34     # 设置关系
35     std_obj1.teachers.add(tea_obj, tea_obj1)
36     std_obj2.teachers.add(tea_obj, tea_obj1)
37
38     return HttpResponse('many to many add...')
39
40
41 def many_find(request):
42     # 1.zs 被哪些老师教过
43     # std_obj = models.Student.objects.get(name='zs')
44     # ret = std_obj.teachers.all()
45     # print(ret)
46
47     # 2.laowang 教过哪些学生
48     tea_obj = models.Teacher.objects.get(name='laowang')
49     ret = tea_obj.student_set.all()  # 类名小写_set.方法名称()
50     print(ret)
51     return HttpResponse('many to many find...')