django中orm的简单操作

数据库模型

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=32)
    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=64)
 
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)
 
    # 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',)

models.py

查询语句

from django.shortcuts import render,HttpResponse
 
# Create your views here.
 
from app01 import models
 
def query(request):
 
    # #####################基于对象查询(子查询)##############################
    #                按字段（publish）
    # 一对多   book  ----------------->  publish
    #               <----------------
    #                 book_set.all()
 
    # 正向查询按字段：
 
    # 查询python这本书籍的出版社的邮箱
 
    # python=models.Book.objects.filter(title="python").first()
    # print(python.publish.email)
 
    # 反向查询按     表名小写_set.all()
 
    # 苹果出版社出版的书籍名称
 
    # publish_obj=models.Publish.objects.filter(name="苹果出版社").first()
    # for obj in publish_obj.book_set.all():
    #     print(obj.title)
 
    #                按字段（authors.all()）
    # 多对多   book  ----------------------->  author
    #               <----------------
    #                  book_set.all()
 
    # 查询python作者的年龄
    # python = models.Book.objects.filter(title="python").first()
    # for author in python.authors.all():
    #     print(author.name ,author.age)
 
    # 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)
 
    #                  按字段 authorDetail
    # 多对多   author  ----------------------->  authordetail
    #                <----------------
    #                  按表名  author
 
    #查询alex的手机号
    # alex=models.Author.objects.filter(name='alex').first()
    # print(alex.authorDetail.telephone)
 
    # 查询家在山东的作者名字
 
    # ad_list=models.AuthorDetail.objects.filter(addr="shandong")
    #
    # for ad in ad_list:
    #     print(ad.author.name)
 
    '''
    对应sql:
       select publish_id from Book where title="python"
       select email from Publish where nid =   1
 
    '''
 
    # #####################基于queryset和__查询（join查询）############################
 
    # 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
    # ret=models.Book.objects.filter(title="python").values("publish__email")
    # print(ret.query)
 
    '''
    select publish.email from Book
    left join Publish on book.publish_id=publish.nid
    where book.title="python"
    '''
 
    # 苹果出版社出版的书籍名称
    # 方式1：
    ret1=models.Publish.objects.filter(name="苹果出版社").values("book__title")
    print("111111111====>",ret1.query)
    #方式2：
    ret2=models.Book.objects.filter(publish__name="苹果出版社").values("title")
    print("2222222222====>", ret2.query)
 
    #查询alex的手机号
    # 方式1：
    ret=models.Author.objects.filter(name="alex").values("authorDetail__telephone")
 
    # 方式2：
    models.AuthorDetail.objects.filter(author__name="alex").values("telephone")
 
    # 查询手机号以151开头的作者出版过的书籍名称以及书籍对应的出版社名称
 
    ret=models.Book.objects.filter(authors__authorDetail__telephone__startswith="").values('title',"publish__name")
    print(ret.query)
 
    return HttpResponse("OK")