DOM操作

from django.shortcuts import render,HttpResponse

# Create your views here.


from .models import *
def query(request):


    #######################基于对象的跨表查询(子查询)#######################
    # '''
    # 一对多：
    #      正向查询按字段
    # Book--------------->Publish
    #     <---------------
    #      反向查询按表名小写_set
    # '''
    # #(1) 查询id为2的书籍对应出版社的邮箱
    # obj=Book.objects.filter(nid=2).first()
    # print(obj.publish.email)
    # ret=obj.publish.email
    # # select publihs_id from Book where nid=2
    # # select   email    from  Publish where nid=（select publihs_id from Book where nid=2）
    #
    # #(2) 橘子出版社出版过的所有的书籍的名字
    # # obj=Publish.objects.filter(name="橘子出版社").first()
    # # ret=obj.book_set.all().values("title")
    #
    # '''
    #    多对多：
    #         正向查询按字段
    #    Book--------------->Author
    #        <---------------
    #         反向查询按表名小写_set
    #         反向查询按xxx
    # '''
    #
    # # 查询围城所有作者的名字
    # obj=Book.objects.filter(title="围城").first()
    # ret=obj.authors.all().values("name")
    # print(ret)
    #
    # # 查询alex出版的书籍个数
    # obj=Author.objects.filter(name="alex").first()
    # ret=obj.book_set.all().count()
    # print(ret)
    #
    # '''
    #        一对一：
    #             正向查询按字段
    #        Book--------------->Author
    #            <---------------
    #             反向查询按表名小写
    # '''
    #
    # # 查询alex的手机号
    # obj=Author.objects.filter(name="alex").first()
    # ret=obj.authorDetail.telephone
    # print(ret)
    #
    # # 住在烟台的作者的名字
    #
    # obj_list=AuthorDetail.objects.filter(addr="烟台")
    # for obj in obj_list:
    #     print(obj.author.name)

    #######################基于queryset和__的跨表查询(join查询)#######################
    '''
    正向查询安字段
    反向查询安表名
    '''
    # (1)查询id为2的书籍对应出版社的邮箱
    # ret=Book.objects.filter(price=100).values("publish__email")
    # print(ret)# [{publish__email:456},{publish__email:456},{publish__email:123}]
    '''
    Book.objects.filter(price=100).values("title","publish__email"):
    queryset=Book.objects.filter(price=100)
    temp=[]
    for obj in queryset:
        temp.append({
            "title":obj.title,
            "publish__email":obj.publish__email
        })
        
    temp
    
    '''

    # # (2)橘子出版社出版过的所有的书籍的名字
    # ret=Publish.objects.filter(name="橘子出版社").values("book__title")
    # print(ret)
    # # (3)查询围城所有作者的名字
    # ret=Book.objects.filter(title="围城").values("authors__name")
    # print(ret)
    # # (4)查询alex出版的书籍个数
    # Author.objects.filter(name="alex").values("book__title").count()
    # # (5)查询alex的手机号
    # ret=Author.objects.filter(name="alex").values("authorDetail__telephone")
    # print(ret)
    # # (6)住在烟台的作者的名字
    # ret=AuthorDetail.objects.filter(addr="烟台").values("author__name")
    # print(ret)


    #####################分组查询##########################
    from django.db.models import Count,Avg
    # # 每一个出版社的名字以及对应出版书籍个数
    # ret=Publish.objects.all().annotate(book_count=Count("book__title")).values("name","book_count")
    # print(ret)
    #
    # # 查询每一个作者的名字以及对应书籍的平均价格
    # ret=Author.objects.all().annotate(books_avg=Avg("book__price")).values("name","books_avg")
    # print(ret)
    #
    #
    # # 查询每一本书 的名字以及作者的个数
    # ret=Book.objects.all().annotate(c=Count("authors")).values("title","c")
    # print(ret)



    # select * from Publish group by id
    # select 哪个字段就按哪个字段group_by
    ret=Book.objects.values("title").annotate(c=Count("*"))
    print(ret)
    # SELECT "app01_book"."title", COUNT(*) AS "c" FROM "app01_book" GROUP BY "app01_book"."title"

    return HttpResponse("OK")

from django.db import models

# Create your models here.



class AuthorDetail(models.Model):
    nid = models.AutoField(primary_key=True)
    birthday = models.DateField()
    telephone = models.BigIntegerField()
    addr = models.CharField(max_length=64)

class Author(models.Model):
    nid = models.AutoField(primary_key=True)
    name = models.CharField(max_length=32)
    age = models.IntegerField()
    # 与AuthorDetail建立一对一的关系
    authorDetail = models.OneToOneField(to="AuthorDetail")

class Publish(models.Model):
    nid = models.AutoField(primary_key=True)
    name = models.CharField(max_length=32)
    city = models.CharField(max_length=32)
    email = models.EmailField()


class Book(models.Model):
    nid = models.AutoField(primary_key=True)
    title = models.CharField(max_length=32)
    publishDate = models.DateField()
    price = models.DecimalField(max_digits=5, decimal_places=2)
    keepNum = models.IntegerField()
    commentNum = models.IntegerField()

    # 与Publish建立一对多的关系,外键字段建立在多的一方
    publish = models.ForeignKey(to="Publish", to_field="nid",)

    # 与Author表建立多对多的关系,ManyToManyField可以建在两个模型中的任意一个，自动创建第三张表
    authors = models.ManyToManyField(to='Author')