ORM中基于对象查询与基于queryset查询

from django.shortcuts import render, HttpResponse

from django.http import JsonResponse

# Create your views here.

from app01 import models

def query(request):

    #########基于对象查询(子查询)###########

    # 一对多  book(publish forkey) ---> publish 正向查询

    # 正向查询 按字段

    # 反向查询 表名_set.all() 一对多

    # 查询python这本书籍的出版社的邮箱

    python = models.Book.objects.filter(title="python").first()  # 对象

    print(python.publish.email)

    # 查询苹果出版社出版的书籍名称 (反向查询 表名小写_set.all())

    # publish_obj = models.Publish.objects.filter(name="苹果出版社").first() #对象

    # print(publish_obj)

    # for obj in publish_obj.book_set.all():

    #     print(obj.title)

    #           按字段(author.all())

    # 多对多 book ---------> author

    #           <---------

    #           book_set.all()

    # 正向查询

    # 查询python的作者的年龄

    # python = models.Book.objects.filter(title="python").first()

    # for author in python.authors.all():

    #     print(author.name,author.age)

    # 反向查询

    # 查询alex出版过的书籍名称

    # alex = models.Author.objects.filter(name="alex").first()

    # for book in alex.book_set.all():

    #     print(book.title)

    # 一对一         按字段authorDetail

    #       author -----------> authordetail

    #             <------------

    #                按表名 author

    # 查询alex的手机号 (正向查询)

    # alex = models.Author.objects.filter(name="alex").first()

    # print(alex.authorDetail.telephone)

    # 查询家在北京的作者名字 (反向查询)

    # obj = models.AuthorDetail.objects.filter(addr="北京").first()

    # print(obj.author.name)

    print("分割线:", "*" * )

    # 如果addr为北京的人很多  执行了若干次的一对一执行

    # obj_list = models.AuthorDetail.objects.filter(addr="北京").all()

    # for first in obj_list:

    #     print(first.author.name)

    """

    查询python这本书籍的出版社的邮箱 models.book.objects.filter(title="python").first().publish.email

    第一步: SELECT "app01_book"."nid", "app01_book"."title", "app01_book"."publishDate", "app01_book"."price

", "app01_book"."publish_id" FROM "app01_book" WHERE "app01_book"."title" = 'python' ORDER BY "app01_boo

k"."nid" ASC LIMIT 1; args=('python',)

    第二步:SELECT "app01_publish"."nid", "app01_publish"."name", "app01_publish"."city", "app01_publish"."e

mail" FROM "app01_publish" WHERE "app01_publish"."nid" = 1; args=(1,)

    即: #若干条子查询 select语句

        select publish_id from Book where title = "python"

        select email from Publish where nid = 

    查询alex手机号 models.author.objects.filter(name="alex").first().authorDetail.telephone

    select authorDetail_id from author where name = "alex"

    select telephone from authordetail where nid = 

    """

    #########基于queryset和__查询 (join)###########

    # 正向查询:按字段__

    # 反向查询:表名小写__

    """

    查询python 这本书籍的出版社的邮箱

    select publish.email from Book left join Publish on book.publish_id = publish.nid where book.title = "python"

    """

    # 查询python 这本书籍的出版社的邮箱 (正向查询)

    ret = models.Book.objects.filter(title="python").values("publish__email")

    #方式2

    models.Publish.objects.filter(book__title="python").values("email")

    print(ret.query)  # ret.query属性 就不需要在setging设置全局了

    """

    SELECT "app01_publish"."email" FROM "app01_book" INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "ap

p01_book"."title" = python

    """

    #查询苹果出版社的书籍名称

    #方式1

    book = models.Publish.objects.filter(name="天空出版社").values("book__title")

    print(book.query)

    #方式2

    book = models.Book.objects.filter(publish__name="天空出版社").values("title")

    print(book.query)

    """

    SELECT "app01_book"."title" FROM "app01_publish"

    LEFT OUTER JOIN "app01_book" ON ("app01_publish"."nid" = "app01_book"."publish_id")

    WHERE "app01_publish"."name" = 天空出版社

    SELECT "app01_book"."title" FROM "app01_publish"

    LEFT OUTER JOIN "app01_book" ON ("app01_book"."publish_id" = "app01_publish"."nid")

    WHERE "app01_publish"."name" = 天空出版社   

    """

    #查询alex的手机号

    alex = models.Author.objects.filter(name="alex").values("authorDetail__telephone")

    print(alex)

    alex  = list(alex)

    print(alex)

    tel = models.AuthorDetail.objects.filter(author__name="alex").values("telephone")

    print(tel)

    #查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称  (五张表)

    book_ret = models.Book.objects.filter(authors__authorDetail__telephone__startswith="").values("title","publish__name")

    print(book_ret)

    publish_ret = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="").values("book__title","name")

    print(publish_ret)

    """

    SELECT "app01_book"."titl

e", "app01_publish"."name" FROM "app01_book" INNER JOIN "app01_book_authors" ON ("app01_book"."nid" = "app01_book_authors"."book_id") INNER

JOIN "app01_author" ON ("app01_book_authors"."author_id" = "app01_author"."nid") INNER JOIN "app01_authordetail" ON ("app01_author"."authorD

etail_id" = "app01_authordetail"."nid") INNER JOIN "app01_publish" ON ("app01_book"."publish_id" = "app01_publish"."nid") WHERE "app01_autho

rdetail"."telephone" LIKE 151% ESCAPE '\'

    """

    # test查询手机号以151开头的作者出版过的书籍名称以及对应的出版社名称  (五张表)

    book = models.Book.objects.filter(authors__authorDetail__telephone__startswith="").values("title","publish__name")

    publish = models.Publish.objects.filter(book__authors__authorDetail__telephone__startswith="").values("book__title","name")

    print("this is test",book,publish)

    ###############################聚合与分组#####################################

    #查询所有书籍的价格和

    from django.db.models import Sum, Count, Avg

    ret = models.Book.objects.all().aggregate(price_sum = Sum("price"))

    print(ret) #ret为字典 {'price_sum': Decimal('710.00')}

    #查询所有作者的平均年龄

    ret = models.Author.objects.all().aggregate(age_avg = Avg("age"))

    print(ret)

    #统计有多少个作者

    ret = models.Author.objects.all().aggregate(num = Count("nid"))

    print(ret)

    #分组

    """

    sql分组

        emp表

        id       name     age     dep

                alex              技术部

                egon              技术部

                wenzhou           运营部

                jc                运营部

    查询每一个部门的人数

    sql:

        select Count(id) from emp group by dep

    orm:

        models.emp.objects.values("dep").annotate(c=Count("id"))

        emp表

    id       name     age     dep_id

            alex

            egon

            wenzhou           

        dep表

    id      name

           技术部

           运营部

    查询每一个部门名称以及对应人数

    sql:

        select * from emp inner join dep on emp.dep_id = dep.id

            id       name     age     dep_id  dep.id dep.name

                    alex                        技术部

                    egon                        运营部

                    wenzhou                     运营部

        select dep.name, Count(*) from emp inner join dep on emp.dep_id = dep.id group by dep.id, dep.name 

    ORM:

        关键点:

                .queryset数据可以调用annotate()

                .annotate进行分组统计，按照前面的select的字段进行group by

                .annotate()返回值依然是queryset对象， 增加了分组统计的键值对

        models.dep.objects.values("name").annotate(c=Count("emp__name")).values("name","c")

        models.emp.objects.values("dep__name").annotate(c=Count("name")).values("dep__name", "c")

        select dep.name, Count(emp.name) as c from dep inner join emp on .. group by dep.name

        select ___ from ___ inner join ___ on ... group by ___

    """

    ret = models.Publish.objects.values("name") #SELECT "app01_publish"."name" FROM "app01_publish"

    print(ret.query)

    from django.db.models import Max

    #查询每一个作者的名字以及出版过的书籍最高价格

    ret = models.Author.objects.values("name").annotate(max_price = Max("book__price")).values("name","max_price")

    print(ret)

    """

    select author.name, Max(book.price) as max_price from author inner join book_authors on ...

                          inner join book   on ...

    group by author.name

    """

    #查询每一个出版社出版过的书籍的平均价格

    ret = models.Publish.objects.values("name").annotate(avg_price = Avg("book__price")).values("name","avg_price")

    print(ret)

    #查询每一本书籍的作者个数

    ret = models.Book.objects.values("title").annotate(author_count = Count("authors__name")).values("title","author_count")  #或者将authors__name换成authors

    print(ret)

    #查询每一个分类的名称以及对应的文章数

    # models.Category.objects.all().annotate(c = Count("article__title")).values("title","c")

    #统计不止2个作者的图书名称: 作者数大于两个  难点

    #先统计每个本书籍的作者个数

    ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).values("title","count")

    print(ret)

    """

    select book.title, Count(author.name) as c  from book inner join book-authors on ..

                        inner join author on ..

    group by book.id having c >

    """

    ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count__gt=).values("title","count")

    print(ret)

    #统计作者为2的图书名称

    ret = models.Book.objects.values("title").annotate(count=Count("authors__name")).filter(count=).values("title","count")

    print(ret)

    #统计出版的每一本价格大于100的书籍

    ret = models.Book.objects.values("title").filter(price__gt=).values("title","price")

    print(ret)

    #统计每一个出版出版的书籍及价格

    ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","book__title")

    print(ret)

    #统计每一个出版社出版的书籍个数

    ret = models.Publish.objects.values("name").annotate(count=Count("book__title")).values("name","count")

    print(ret)

    #统计每一个出版社出版大于100的书籍名称

    ret = models.Publish.objects.values("name").annotate().filter(book__price__gt=).values("name","book__title","book__price")

    print(ret)

    return HttpResponse("ok")

from django.db import models

# Create your models here.

from django.db import models

# Create your models here.

class Author(models.Model):

    nid = models.AutoField(primary_key=True)

    name=models.CharField( max_length=)

    age=models.IntegerField()

    # 与AuthorDetail建立一对一的关系

    authorDetail=models.OneToOneField(to="AuthorDetail",on_delete=models.CASCADE)

class AuthorDetail(models.Model):

    nid = models.AutoField(primary_key=True)

    birthday=models.DateField()

    telephone=models.BigIntegerField()

    addr=models.CharField( max_length=)

class Publish(models.Model):

    nid = models.AutoField(primary_key=True)

    name=models.CharField( max_length=)

    city=models.CharField( max_length=)

    email=models.EmailField()

class Book(models.Model):

    nid = models.AutoField(primary_key=True)

    title = models.CharField( max_length=)

    publishDate=models.DateField()

    price=models.DecimalField(max_digits=,decimal_places=)

    publish=models.ForeignKey(to="Publish",to_field="nid",on_delete=models.CASCADE)

    authors=models.ManyToManyField(to='Author',)  #多对多关联字段