Django_ORM数据表查询总结

Posted 2020-10-14

class Author(models.Model):
    ‘‘‘作者表‘‘‘
    name = models.CharField(max_length=32)
    book = models.ManyToManyField(to="Book")
    # def __str__(self):
    #     return self.name

class Book(models.Model):
    ‘‘‘书表‘‘‘
    title = models.CharField(max_length=32)
    price = models.CharField(max_length=32)
    publish = models.ForeignKey(to="Publish")
    # def __str__(self):
    #     return self.title
    #egon出版过的书的出版社信息

class Publish(models.Model):
    ‘‘‘出版社‘‘‘
    address = models.CharField(max_length=32)
    # def __str__(self):
    #     return self.address

# author = models.Author.objects.all()   #查询到所有的作者对象queryset   author多对多book
# book = models.Book.objects.all()  # 查询到所有的书籍对象queryset       book多对一publish
# publish = models.Publish.objects.all()   #查询到所有的出版社对象queryset
# #================================================字段查询============================================================
# for te in author:
#     print("======author",te.name)      #查询自己表内的信息
#     print("======author_book",te.book.first().title)      #通过自己查找多对多的字段
#     print("======author_book_publish",te.book.first().publish.address)      #通过自己查找多对多的字段,然后查找多对一字段
# for te in book:
#     print("========tetetet",te)
#     print("======book",te.title,te.price)      #查询自己表内的信息
#     print("========book_publish",te.publish.address)     #通过自己查询多对一的出版社表
#     print("==========book_author",te.author_set.first())     #通过自己反向查找作者姓名
# for te in publish:
#     print("=====publish",te.address)      #查询自己表内的信息
#     print("=====publish_book",te.book_set.first().title)
#     print("=======publish_book_author",te.book_set.first().author_set.first())
#
#
# author_book_publish = author.first().book.all().first().title
# print("==================================",author_book_publish)
# #============================================双下划线正向查询===========================================================

# author = models.Author.objects.all()  # 查询到所有的作者对象queryset   author多对多book
# book = models.Book.objects.all()  # 查询到所有的书籍对象queryset       book多对一publish
# publish = models.Publish.objects.all()  # 查询到所有的出版社对象queryset

# book_title = author.filter(name="egon").values("book__title")      #在author表中查book标的title
# book_price = author.filter(name="egon").values("book__price")      #在author表中查book表的price
# book_publish_address = author.filter(name="egon").values("book__publish__address")   #在author表中二次关联查找出版社
# print("============book_title|book_price",book_title,book_price)
# print("============book_publish_addredd",book_publish_address)

# #============================================双下划线反向查询===========================================================
# book_title = publish.filter(address="北京").values("book__title")
# book_price = publish.filter(address="北京").values("book__price")
# publish_book = publish.filter(address="北京").values("book__author")
# publish_author_book = publish.filter(address="北京").values("book__author__name")
# print("============book_title|book_price",book_title,book_price)
# print("============publish_book",publish_book)
# print("============publish_author_book",publish_author_book)

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