ORM 对表操作 详解
- 2019 年 10 月 8 日
- 筆記
目录
ORM对表操作详解
表结构
- 作者表,作者详细信息表,出版社表,书籍表
from django.db import models # 作者表(一对一作者详细信息表) #比较常用的信息放到这个表里面 class Author(models.Model): name = models.CharField(max_length=32, verbose_name='作者姓名') age = models.IntegerField(verbose_name='年龄') # authorDetail=models.OneToOneField(to="AuthorDetail",to_field="nid",on_delete=models.CASCADE) # #to关联表,to_field指定字段,on_delete设置级联删除 authorDetail = models.OneToOneField(to='AuthorDetail', verbose_name='作者详细信息') # 一对一到AuthorDetail表 生成为表字段之后,会自动变为authorDetail_id这样有一个名称 # OneToOneField(一对一关系) 相当于 foreign+unique def __str__(self): return self.name # 作者详细信息表 class AuthorDetail(models.Model): birthday = models.DateField(verbose_name='出生日期') # telephone=models.BigIntegerField()#不方便查询,比如模糊查询,占资源比较多 telephone = models.CharField(max_length=32, verbose_name='电话') # CharField推荐使用来存储电话 addr = models.CharField(max_length=64, verbose_name='住址') def __str__(self): return self.addr # 出版社表 #(一对多 书籍表)是 class Publish(models.Model): name = models.CharField(max_length=32, verbose_name='出版社名称') city = models.CharField(max_length=32, verbose_name='出版社所在城市') email = models.EmailField(verbose_name='出班社邮箱') # EmailField本质上是charfield做了一些邮箱规则的效验 def __str__(self): return self.name # 书籍表 class Book(models.Model): nid = models.AutoField(primary_key=True) title = models.CharField(max_length=32, verbose_name='书名') publishDate = models.DateField(verbose_name='出版日期') price = models.DecimalField(max_digits=5, decimal_places=2, verbose_name='价格') # max_digits小数总位数,decimal_places小数部分位数 publishs = models.ForeignKey(to="Publish", verbose_name='出版社') authors = models.ManyToManyField(to='Author', verbose_name='作者') def __str__(self): return self.title
ORM对表的 增 删 改 查
- 增加
一对一 models.Author.objects.create(name='xx',age=18,authorDetail=mdoels.AuthorDetail.Objects.get(id=1)) models.Author.objects.create(name='xx',age=18,authorDetail_id=2) 一对多 models.Book.objects.create(xx=xx,publishs=mdoels.Publish.Objects.get(id=1)) models.Book.objects.create(xx=xx,publishs_id=2) 多对多 book_obj = models.Book.objects.get(id=1) book_obj.authors.add(*[author_obj1,author_obj2,..]) book_obj.authors.add(*[1,2,3...])
- 删
一对一 models.Author.objects.filter(id=1).delete() 一对多 models.Book.objects.filter(id=1).delete() 多对多 book_obj = models.Book.objects.get(id=1) book_obj.authors.remove(1,2,3,4) book_obj.authors.remove(*[1,2,...]) book_obj.authors.clear() book_obj.authors.set(['1','2',...]) :clear -- add
- 改
一对一 models.Author.objects.filter(id=1).update( authorDetail=mdoels.AuthorDetail.Objects.get(id=1) ) models.Author.objects.filter(id=1).update( authorDetail_id=2, ) 一对多 models.Book.objects.filter(id=1).update( publishs=mdoels.Publish.Objects.get(id=1) ) models.Book.objects.filter(id=1).update( publishs_id=2, ) 多对多 book_obj.authors.set(['1','2',...]) :clear -- add
基于对象的跨表查询 — 类似于子查询
- 正向查询和反向查询
- 关系属性(字段)写在哪个类(表)里面,从当前类(表)的数据去查询它关联类(表)的数据叫做正向查询,反之叫做反向查询
#查询 # 一对一 # 正向查询 #1 查询崔老师的电话号 # author_obj = models.Author.objects.filter(name='崔老师').first() # # print(author_obj.authorDetail) #辽宁峨眉山 # # print(author_obj.authorDetail.telephone) #444 # #2 反向查询 # #2 查询一下这个444电话号是谁的. # author_detail_obj = models.AuthorDetail.objects.get(telephone='444') # print(author_detail_obj.author) #崔老师 # print(author_detail_obj.author.name) #崔老师 ''' 正向查询:Authorobj.authorDetail,对象.关联属性名称 Author----------------------------------->AuthorDetail <----------------------------------- 反向查询:AuthorDetailobj.author ,对象.小写类名 ''' # 一对多 # 查询一下李帅的床头故事这本书的出版社是哪个 # 正向查询 book_obj = models.Book.objects.get(title='李帅的床头故事') print(book_obj.publishs) #B哥出版社 print(book_obj.publishs.name) #B哥出版社 # B哥出版社出版社出版了哪些书 # 反向查询 pub_obj = models.Publish.objects.get(name='B哥出版社') print(pub_obj.book_set.all()) #<QuerySet [<Book: 李帅的床头故事>, <Book: 李帅的床头故事2>]> ''' 正向查询 book_obj.publishs 对象.属性 Book ---------------------------------------------> Publish <---------------------------------------------- 反向查询 publish_obj.book_set.all() 对象.表名小写_set ''' # 多对多 # 李帅的床头故事这本书是谁写的 # 正向查询 book_obj = models.Book.objects.get(title='李帅的床头故事') print(book_obj.authors.all()) # 高杰写了哪些书 author_obj = models.Author.objects.get(name='高杰') print(author_obj.book_set.all()) ''' 正向查询 book_obj.authors.all() 对象.属性 Book ---------------------------------------------> Author <---------------------------------------------- 反向查询 author_obj.book_set.all() 对象.表名小写_set '''
基于双下划的跨表查询 — 连表 join
- 正向查询和反向查询
#查询 # 一对一 # 1. 查询崔老师的电话号 # 方式1 正向查询 # obj = models.Author.objects.filter(name='崔老师').values('authorDetail__telephone') # print(obj) #<QuerySet [{'authorDetail__telephone': '444'}]> # 方式2 反向查询 # obj = models.AuthorDetail.objects.filter(author__name='崔老师').values('telephone','author__age') # print(obj) #<QuerySet [{'telephone': '444'}]> # 2. 哪个老师的电话是444 # 正向 # obj = models.Author.objects.filter(authorDetail__telephone='444').values('name') # print(obj) # 反向 # obj = models.AuthorDetail.objects.filter(telephone='444').values('author__name') # print(obj) # 一对多 # 查询一下李帅的床头故事这本书的出版社是哪个 # obj = models.Book.objects.filter(title='李帅的床头故事').values('publishs__name') # print(obj) #<QuerySet [{'publishs__name': 'B哥出版社'}]> # obj = models.Publish.objects.filter(book__title='李帅的床头故事').values('name') # obj = models.Publish.objects.filter(xx__title='李帅的床头故事').values('name') # print(obj) # B哥出版社出版社出版了哪些书 # obj = models.Publish.objects.filter(name='B哥出版社').values('book__title') # print(obj) #<QuerySet [{'book__title': '李帅的床头故事'}, {'book__title': '李帅的床头故事2'}]> # obj = models.Book.objects.filter(publishs__name='B哥出版社').values('title') # print(obj) #<QuerySet [{'title': '李帅的床头故事'}, {'title': '李帅的床头故事2'}]> # 李帅的床头故事这本书是谁写的 # obj = models.Book.objects.filter(title='李帅的床头故事').values('authors__name') # print(obj) # obj = models.Author.objects.filter(book__title='李帅的床头故事').values('name') # print(obj) #<QuerySet [{'name': '高杰'}, {'name': '崔老师'}]> #高杰写了哪些书 # obj = models.Book.objects.filter(authors__name='高杰').values('title') # print(obj) # obj = models.Author.objects.filter(name='高杰').values('book__title') # print(obj) #进阶的 # B哥出版社 出版的书的名称以及作者的名字 # obj = models.Book.objects.filter(publishs__name='B哥出版社').values('title','authors__name') # print(obj) #<QuerySet [{'title': '李帅的床头故事', 'authors__name': '高杰'}, {'title': '李帅的床头故事', 'authors__name': '崔老师'}, {'title': '李帅的床头故事2', 'authors__name': '崔老师'}, {'title': '李帅的床头故事2', 'authors__name': '王涛'}]> ''' SELECT app01_book.title,app01_author.name from app01_publish INNER JOIN app01_book on app01_publish.id=app01_book.publishs_id INNER JOIN app01_book_authors on app01_book.nid = app01_book_authors.book_id INNER JOIN app01_author ON app01_author.id = app01_book_authors.author_id where app01_publish.name='B哥出版社'; :param request: :return: ''' # obj = models.Publish.objects.filter(name='B哥出版社').values('book__title','book__authors__name') # print(obj) # obj = models.Author.objects.filter(book__publishs__name='B哥出版社').values('name','book__title') # print(obj) # authorDetail author book publish # 手机号以4开头的作者出版过的所有书籍名称以及出版社名称 # ret = models.AuthorDetail.objects.filter(telephone__startswith='4').values('author__book__title','author__book__publishs__name') # print(ret) #QuerySet [{'author__book__title': '李帅的床头故事', 'author__book__publishs__name': 'B哥出版社'}, {'author__book__title': '李帅的床头故事2', 'author__book__publishs__name': 'B哥出版社'}]> #查询一下B哥出版社出版了哪些书 # obj = models.Publish.objects.filter(name='B哥出版社').first() # print(obj.xx.all())
ORM对表的操作示例
操作示例 点击查看(代码)
System.out.println("Hello to see U!"); ```python 1.1 一对一增加 new_author_detail = models.AuthorDetail.objects.create( birthday='1979-08-08', telephone='138383838', addr='黑龙江哈尔滨' ) obj = models.AuthorDetail.objects.filter(addr='山西临汾').first() 方式1 models.Author.objects.create( name='王涛', age='40', authorDetail=new_author_detail, ) 方式2 常用 models.Author.objects.create( name='王涛', age='40', authorDetail_id=obj.id, ) 1.2 一对多增加 方式1 obj = models.Publish.objects.get(id=2) models.Book.objects.create( title = '李帅的床头故事', publishDate='2019-07-22', price=3, # publishs=models.Publish.objects.get(id=1), publishs=obj, ) 方式2 常用 models.Book.objects.create( title='李帅的床头故事2', publishDate='2019-07-21', price=3.5, # publishs=models.Publish.objects.get(id=1), publishs_id=obj.id ) 1.3 多对多增加 方式1 常用(效率高) book_obj = models.Book.objects.get(nid=1) book_obj.authors.add(*[1,2]) 方式2 author1 = models.Author.objects.get(id=1) author2 = models.Author.objects.get(id=3) book_obj = models.Book.objects.get(nid=5) book_obj.authors.add(*[author1,author2]) ``` ### ORM对表的 删 操作 ```python #一对一 和 一对多 的删除和单表删除是一样的. #一对一 表一外键关联到表二,表一删除,不影响表2,表2删除会影响表1 models.AuthorDetail.objects.get(id=2).delete() models.Author.objects.get(id=3).delete() 一对多 models.Publish.objects.get(id=1).delete() models.Book.objects.get(nid=1).delete() 多对多关系删除 book_obj = models.Book.objects.get(nid=6) book_obj.authors.remove(6) #authors是表中的关联对象 删除单个 book_obj.authors.remove(*[5,6]) #删除多个 book_obj.authors.clear() #全部关联对象删除 book_obj.authors.add(*[1,]) #添加 book_obj.authors.set('1') #删除之前关系添加新关系 book_obj.authors.set(['5','6']) #删除然后更新 多个 ``` ### ORM对表的 更新 操作 ```python 一对一 更新 models.Author.objects.filter(id=5).update( name='崔老师', age=16, # authorDetail=models.AuthorDetail.objects.get(id=5), authorDetail_id=4, ) 一对多 更新 models.Book.objects.filter(pk=4).update( title='B哥的往事2', # publishs=models.Publish.objects.get(id=3), publishs_id=3, ) #一对多 models.Publish.objects.filter(pk=2).update( id=4, # 没有级联更新,报错!! ) ``` ### ORM对表的 查询 操作(重点 ) ```python #查询 # 一对一 # 1. 查询崔老师的电话号 # 方式1 正向查询 # obj = models.Author.objects.filter(name='崔老师').values('authorDetail__telephone') # print(obj) # #方式2 反向查询 # obj = models.AuthorDetail.objects.filter(author__name='崔老师').values('telephone','author__age') # print(obj) # # 2. 哪个老师的电话是444 # 正向 # obj = models.Author.objects.filter(authorDetail__telephone='444').values('name') # print(obj) # 反向 # obj = models.AuthorDetail.objects.filter(telephone='444').values('author__name') # print(obj) # 一对多 # 查询一下李帅的床头故事这本书的出版社是哪个 # obj = models.Book.objects.filter(title='李帅的床头故事').values('publishs__name') # print(obj) # obj = models.Publish.objects.filter(book__title='李帅的床头故事').values('name') # print(obj) # B哥出版社出版社出版了哪些书 # obj = models.Publish.objects.filter(name='B哥出版社').values('book__title') # print(obj) # # obj = models.Book.objects.filter(publishs__name='B哥出版社').values('title') # print(obj) # # 李帅的床头故事这本书是谁写的 # obj = models.Book.objects.filter(title='李帅的床头故事').values('authors__name') # print(obj) # obj = models.Author.objects.filter(book__title='李帅的床头故事').values('name') # print(obj) # # 高杰写了哪些书 # obj = models.Book.objects.filter(authors__name='高杰').values('title') # print(obj) # obj = models.Author.objects.filter(name='高杰').values('book__title') # print(obj) # 进阶的 # B哥出版社 出版的书的名称以及作者的名字 # obj = models.Book.objects.filter(publishs__name='B哥出版社').values('title','authors__name') # print(obj) # ''' SELECT app01_book.title,app01_author.name from app01_publish INNER JOIN app01_book on app01_publish.id=app01_book.publishs_id INNER JOIN app01_book_authors on app01_book.nid = app01_book_authors.book_id INNER JOIN app01_author ON app01_author.id = app01_book_authors.author_id where app01_publish.name='B哥出版社'; :param request: :return: ''' # obj = models.Publish.objects.filter(name='B哥出版社').values('book__title','book__authors__name') # print(obj) # obj = models.Author.objects.filter(book__publishs__name='B哥出版社').values('name','book__title') # print(obj) # authorDetail author book publish # 手机号以4开头的作者出版过的所有书籍名称以及出版社名称 # ret = models.AuthorDetail.objects.filter(telephone__startswith='4').values('author__book__title','author__book__publishs__name') # print(ret) # QuerySet [{'author__book__title': '李帅的床头故事', 'author__book__publishs__name': 'B哥出版社'}, {'author__book__title': '李帅的床头故事2', 'author__book__publishs__name': 'B哥出版社'}]> # 查询一下B哥出版社出版了哪些书 # obj = models.Publish.objects.filter(name='B哥出版社').first() # print(obj.xx.all()) ```
正向查 与 反向查
- 正向查反向查(从设置表关系的那张表查另一张就是正向,反之就是反向查)
related_name 给反向查询的小写表名起别名,以后反向查询调用都用这个别名
作 者：郭楷丰
