Python學習之路—2018/6/26

標籤：bubuko   inf   from   djang   app   date   name   欄位   S3   

Python學習之路—2018/6/261.ORM單表操作刪除與修改記錄

>>> ret = Book.objects.filter(title="go").delete()(1, {‘app01.Book‘: 1})>>> Book.objects.filter(price=115).update(price=120)

多表操作建立模型

一對一

models.OneToOneField(to="表名", on_delete=models.CASCADE)

一對多

models.ForeignKey(to="表名", to_field="欄位名", on_delete=models.CASCADE)

多對多

models.ManyToManyField(to="表名")

models.py

from django.db import modelsclass Author(models.Model):    nid = models.AutoField(primary_key=True)    name = models.CharField(max_length=32)    age = models.IntegerField()    # 與AuthorDetail建立一對一關聯性    author_detail = models.OneToOneField(to="AuthorDetail", on_delete=models.CASCADE)class AuthorDetail(models.Model):    aid = models.AutoField(primary_key=True)    birthday = models.DateField()    telephone = models.BigIntegerField()    addr = models.CharField(max_length=64)class Publish(models.Model):    pid = models.AutoField(primary_key=True)    name = models.CharField(max_length=32)    city = models.CharField(max_length=32)    email = models.EmailField()class Book(models.Model):    bid = models.AutoField(primary_key=True)    title = models.CharField(max_length=32)    publishDate = models.DateField()    price = models.DecimalField(max_digits=5, decimal_places=2)    # 與Publish建立一對多關聯性，外鍵欄位建立在多的一方    publish = models.ForeignKey(to="Publish", to_field="pid", on_delete=models.CASCADE)    """        publish_id INT,        FOREIGN KEY(publish_id) REFERENCES publish(pid)    """    # 與Author建立多對多關係    authors = models.ManyToManyField(to="Author")    """        CREATE TABLE book_author(            id INT PRIMARY KEY AUTO_INCREMENT,            book_id INT,            author_id INT,            FOREIGN KEY(book_id) REFERENCES Book(bid),            FOREIGN KEY(author_id) REFERENCES Author(nid),        )    """

運行結果：

注意：

• on_delete = models.CASCADE在使用一對以及一對多時需要用到
• 外鍵欄位會自動添加_id，比如publish = models.ForeignKey()執行後產生publish_id
• 需要在settings.py中配置app01

添加記錄

一對多

Book.objects.create(title="壞蛋是怎樣煉成的", publishDate="2017-01-02", price=125, publish_id=1)

運行結果：

>>> book = Book.objects.get(bid=1)>>> print(book.bid)1>>>print(book.title)壞蛋是怎樣煉成的>>> print(book.publishDate)2017-01-02>>> print(book.price)125.00>>> print(book.publish)Publish object (1)>>> print(book.publish.name)中國城市出版社>>> print(book.publish.email)[email protected]

Python學習之路—2018/6/26