BBS - 首页、个人站点、ORM

from django.db import models

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",on_delete=models.CASCADE,related_name=‘authors‘)

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",on_delete=models.CASCADE)

    # 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‘)

from django.shortcuts import render,HttpResponse

from app01.models import *

def query(request):

    ###################### 基于对象得跨表查询 （子查询）######################
    """
    一对多： Book  -------> Publish
            正向查询按字段   反向查询按表名 小写_set
    """


    # 1.查询 id=2 得书籍对应得出版社得邮箱  正向
    ret = Book.objects.filter(nid=2).first().publish.email

    # 2.橘子出版社出版过得所有书籍得名字    反向
    ret = Publish.objects.filter(name=‘橘子出版社‘).first().book_set.all().values(‘title‘)


    """
    多对多： Book  -------> Author
            正向查询按字段   反向查询按表名 小写_set
    """
    # 1. 查询金瓶mei所有作者得名字   正向
    ret = Book.objects.filter(title=‘金瓶mei‘).first().authors.all().values(‘name‘)

    # 2.作者alex 出版过得书籍得个数  反向
    ret = Author.objects.filter(name=‘alex‘).first().book_set.all().values(‘title‘)
    ret = Author.objects.filter(name=‘alex‘).first().book_set.all().count()


    """
    一对一： Author  -------> AuthorDetail
            正向查询按字段   反向查询按表名 小写  或者自定义得 related_name=‘authors‘
    """
    # 1.查询alex得手机号   正向
    ret = Author.objects.filter(name=‘alex‘).first().authorDetail.telephone

    # 2.住在烟台得作者得名字  反向
    ret = AuthorDetail.objects.filter(addr=‘烟台‘).first().authors.name
    ret = AuthorDetail.objects.filter(addr=‘烟台‘)
    for i in ret:
        print(i.authors.name)


    ###########################################
    # 基于对象得跨表查询 （子查询）

    """
       SELECT 
         "app01_book"."nid", 
         "app01_book"."title", 
         "app01_book"."publishDate", 
         "app01_book"."price",
         "app01_book"."publish_id" 
     FROM "app01_book"
        WHERE 
         "app01_book"."nid" = 1 
        ORDER BY 
         "app01_book"."nid" ASC LIMIT 1; args=(1,)

    SELECT 
       "app01_publish"."nid",
       "app01_publish"."name", 
       "app01_publish"."city",
       "app01_publish"."email" 
     FROM "app01_publish" 
     WHERE 
     "app01_publish"."nid" = 1; args=(1,)

    """


    ###################### 基于queryset和__ 得跨表查询 ######################

    """
    正向查询按字段 反向查询按表名
    """
    # 1.查询 价格为100 得书籍对应得出版社得邮箱
    ret = Book.objects.filter(price=100).values(‘publish__email‘)
    """
    values:内部
    queryset = Book.objects.filter(price=100)
    temp = []
    for obj in queryset:
        temp.append({
            ‘title‘:obj.title,
            ‘publish_email‘:obj.publish_email
        })
    temp
    """

    # 2.橘子出版社出版过得所有书籍得名字
    ret = Publish.objects.filter(name=‘橘子出版社‘).values("book__title")
    ret = Book.objects.filter(publish__name=‘橘子出版社‘).values(‘title‘)

    # 1. 查询金瓶mei所有作者得名字
    ret = Book.objects.filter(title=‘金瓶mei‘).values(‘authors__name‘)
    ret = Author.objects.filter(book__title=‘金瓶mei‘).values(‘name‘)

    # 2.作者alex 出版过得书籍得个数
    ret = Author.objects.filter(name=‘alex‘).values(‘book__title‘).count()
    ret = Book.objects.filter(authors__name=‘alex‘).values(‘title‘).count()

    # 1.查询alex得手机号
    ret = Author.objects.filter(name=‘alex‘).values(‘authorDetail__telephone‘)
    ret = AuthorDetail.objects.filter(authors__name=‘alex‘).values(‘telephone‘)

    # 2.住在烟台得作者得名字
    ret = Author.objects.filter(authorDetail__addr=‘烟台‘).values(‘name‘)
    ret = AuthorDetail.objects.filter(addr=‘烟台‘).values(‘authors__name‘)


    ###########################################
    # 基于queryset和__ 得跨表查询

    """
        SELECT 
          "app01_book"."title", 
          "app01_book"."price" 
        FROM 
          "app01_book" 
        INNER JOIN "app01_publish" ON 
          ("app01_book"."publish_id" = "app01_publish"."nid")
        WHERE 
          "app01_publish"."name" = ‘人名出版社2‘ LIMIT 21; args=(‘人名出版社2‘,)
    
    """


    ###################### 分组查询(annotate) 与 聚合查询（avg count sum min）######################
    # 员工表 emp  部门表 dep
    """
    单表分组
        sql:
            select dep,AVG(salary) from emp group by dep
        
        ORM查询
            Emp.objects.values(‘dep‘).annotate(dep_avg = AVG(salary)).values(‘dep‘,‘dep_avg‘)
            
    多表分组
        sql：
            select AVG(salary) from emp group by dep_id
            
            select dep.name,AVG(emp.salary) from emp inner join dep on (emp.dep_id == dep.id) group by emp.dep_id
                        
        ORM查询：
            ...
            ...
               
    """

    # 1.每个出版社出版过得书名称，书得个数
    from django.db.models import Count,Avg

    # ret = Publish.objects.all().annotate() # 每个出版社对象 被分为一个组
    # select * from publish group by id

    ret = Publish.objects.all().annotate(book_count = Count(‘book__title‘)).values(‘name‘,‘book_count‘)

    # 2.每一个作者名字以及对应书籍得平均价格
    ret = Author.objects.all().annotate(books_avg = Avg(‘book__price‘)).values(‘name‘,‘books_avg‘)

    # 3.查询每一本书得名字以及作者得个数
    ret = Book.objects.all().annotate(authors_count = Count(‘authors‘)).values(‘title‘,‘authors_count‘)


    # 单表分组查询？
    Book.objects.all().annotate()  # 每一个book 得 id group by

    # select 哪个字段 就按 哪个字段 group by
    ret = Book.objects.all().values(‘title‘).annotate(c = Count(‘*‘)).values(‘title‘,‘c‘)
    #  SELECT "app01_book"."title", COUNT(*) AS "c" FROM "app01_book" GROUP BY "app01_book"."title"; args=()


    ###########################################

    # from django.core import serializers    # 将quertset转化成json
    # ret = serializers.serialize(‘json‘,ret)
    # return HttpResponse(ret)

    # import json
    # return HttpResponse(json.dumps(list(ret),ensure_ascii=False))

    print(ret)
    return HttpResponse(ret)