# -------------------------------------------------------------------------------------------------------- # 三张表 出版社表 书籍表 作者表 # # # 书籍表 # class Book(models.Model): # name = models.CharField(max_length=20) # price = models.IntegerField() # pub_date = models.DateField() # publish = models.ForeignKey("Publish") # #authors = models.ManyToManyField("Author") #一般创建多对多关系 自己也可以创建一个多对多表关系 推荐单建立一个多表 # # authors 对应Author的id == authors_id authors.列名 能取到Author的数据 # def __str__(self): # return self.name # # class Meta: # db_table = "Book" # # 出版社表 # class Publish(models.Model): # name = models.CharField(max_length=32) # city = models.CharField(max_length=32) # # def __str__(self): # return self.name # # class Meta: # db_table = "Publish" # # 推荐自己创建一个多表 这种比较灵活 # # class Book_Author(models.Model): # # book=models.ForeignKey("Book") # # author=models.ForeignKey("Author") # # 作者表 # class Author(models.Model): # name = models.CharField(max_length=32) # age = models.IntegerField(default=20) # # def __str__(self): # return self.name # # class Meta: # db_table = "Author" # -------------------------------------------------------------------------------------------------------- # -------------------------------------------------------------------------------------------------------- # 多表关系 一对多操作 # 添加数据 # Book.objects.create(name="python", price=77, pub_date="2017-12-12", publish_id=2) # # publish_obj=Publish.objects.filter(name="人民出版社")[0] # Book.objects.create(name="GO",price=23,pub_date="2017-05-12",publish=publish_obj) # book_obj=Book.objects.get(name="python") # 是一个对象 # print(type(book_obj)) # print(book_obj.name) # print(book_obj.pub_date) # # #一对多：book_obj.publish--------一定是一个对象 # print(book_obj.publish.name) # print(book_obj.publish.city) # print(type(book_obj.publish)) # # 查询人民出版社出过的所有书籍名字和价格 # select name,price from Book where publish_id in (select id from Publish where name="人民出版社"); # 方式一： # pub_obj = Publish.objects.filter(name="人民出版社")[0] # ret = Book.objects.filter(publish=pub_obj).values("name", "price") # print(ret) # 方式二 # pub_obj = Publish.objects.filter(name="人民出版社")[0] # print(pub_obj.book_set.all().values("name","price")) # print(type(pub_obj.book_set.all())) # 方式三 推荐用这个 正向查询 神奇的双下划线 __ # 通过 filter values (双下换线)进行多对多的关联查询（形式和一对多） # # 查询人民出版社出的书名 和 书的价格 # SELECT `Book`.`name`, `Book`.`price` FROM `Book` INNER JOIN `Publish` ON (`Book`.`publish_id` = `Publish`.`id`) WHERE `Publish`.`name` = '人民出版社' # ret=Book.objects.filter(publish__name="人民出版社").values("name","price") # print(ret) # # python这本书出版社的名字 注意book要小写 # select name from Publish where id in (select publish_id from Book where name="python"); # SELECT `Publish`.`name` FROM `Publish` INNER JOIN `Book` ON (`Publish`.`id` = `Book`.`publish_id`) WHERE `Book`.`name` = 'python' # ret2 = Publish.objects.filter(book__name="python").values("name") # print(ret2) # ret3 = Book.objects.filter(name="python").values("publish__name") # print(ret3) # # 北京城市出的所有书 # select name from Book where publish_id in (select id from Publish where city="bj") # SELECT `Book`.`name` FROM `Book` INNER JOIN `Publish` ON (`Book`.`publish_id` = `Publish`.`id`) WHERE `Publish`.`city` = 'bj' # ret4 = Book.objects.filter(publish__city="bj").values("name") # print(ret4) # 查询一段时间内出过书的出版社 # SELECT `Publish`.`name` FROM `Book` INNER JOIN `Publish` ON (`Book`.`publish_id` = `Publish`.`id`) WHERE (`Book`.`pub_date` < '2017-07-01' AND `Book`.`pub_date` > '2017-01-01') # ret5=Book.objects.filter(pub_date__lt="2017-07-01",pub_date__gt="2017-01-01").values("publish__name") # print(ret5) # -------------------------------------------------------------------------------------------------------- # -------------------------------------------------------------------------------------------------------- # 多多关系 对对多操作 # 通过对象的方式绑定关系 # book_obj=Book.objects.get(id=3) # print(book_obj.authors.all()) # print(type(book_obj.authors.all())) #查询id为2的作者出的书 # author_obj=Author.objects.get(id=2) # print(author_obj.book_set.all()) # 多表操作 增加数据 # book_obj=Book.objects.get(id=37) # author_objs=Author.objects.all() # book_obj.authors.add(*author_objs) # 多表操作 删除数据 # # book_obj.authors.remove(*author_objs) # book_obj.authors.remove(4) # 创建第三张表 # Book_Author.objects.create(book_id=38,author_id=1) # Book_Author.objects.create(book_id=35,author_id=1) # Book_Author.objects.create(book_id=37,author_id=1) # 查找book id是36的作者 # select name from Author where id in (select author_id from Book_Author where book_id = 35); # ret = Author.objects.filter(book_author__book__id="35") # obj_id = Book.objects.filter() # print(ret)
# 外键找外键关联的表 直接用fk找
# 没外键找和它有关联表用 外键的类_set找 注意 外键类小写 或者在外键上加上 related_name='自己的类名' 注意小写 ret = Book.objects.get(id=36).authors.all().values("name") print(ret) # zhangsan出过的书籍名称及价格 # select name,price from Book where id in (select book_id from Book_Author where author_id in(select id from Author where name="zhangsan"))); # ret2=Book.objects.filter(book_author__author__name="zhangsan").values("name","price") # ret2=Book.objects.filter(authors__name="zhangsan").values("name","price") # print(ret2) # ret1 = Author.objects.get(name="zhangsan").book_set.values("name","price") ret1 = Author.objects.get(name="zhangsan").book_set.all() print(ret1) # 找出 linux运维 这本书的作者是谁 #SELECT `Author`.`name` FROM `Author` INNER JOIN `Book_Author` ON (`Author`.`id` = `Book_Author`.`author_id`) INNER JOIN `Book` ON (`Book_Author`.`book_id` = `Book`.`id`) WHERE `Book`.`name` = 'linux运维'; #select name from Author where id in (select author_id from Book_Author where book_id in (select id from Book where name = "linux运维"));; # ret = Author.objects.filter(book_author__book__name="linux运维").values("name") ret2 = Book.objects.get(name="linux运维").authors.all().values("name") print(ret2) # 聚合函数 aggregate # ret=Book.objects.all().aggregate(Avg("price")) # ret=Book.objects.all().aggregate(Sum("price")) # ret=Book.objects.filter(authors__name="alex").aggregate(alex_money=Sum("price")) # ret=Book.objects.filter(authors__name="alex").aggregate(Count("price")) # print(ret) # ret=Book.objects.values("authors__name").annotate(Sum("price")) # print(ret) # ret=Publish.objects.values("name").annotate(abc=Min("book__price")) # print(ret) # b=Book.objects.get(name="GO",price=77) # print(b) # Book.objects.all().update(price=F("price")+10) # ret=Book.objects.filter(Q(name__contains="G")) # print(ret) # ret=Book.objects.filter(Q(name="GO"),price=87) # print(ret) # ret=Book.objects.filter(price=200) # for i in ret: # print(i.price) # # Book.objects.all().update(price=200) # ret = Book.objects.filter(price=100) # for i in ret: # print(i.price) # if ret.exists(): # print("ok") # ret=ret.iterator() # print(ret) # # for i in ret: # print(i.name) # # for i in ret: # print(i.name)