一、创建多表模型
一对一:OneToOneField
一对多:ForeignKey
多对多:ManyToManyField
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创建表时,会自动添加一个nid字段,并且自增,所以id可以不用手动创建
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OneToOneField和ForeignKey会自动在后面加上" _id "
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ManyToManyField会自动创建第三张表
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创建表的类,OneToOneField、ForeignKey和ManyToManyField中的to后的主表,
1、如果用双引号包裹,那么创建主表的类在上在下都可以2、如果不用双引号包裹,那么创建主表的类就必须在从表的上方
二、一对多增删改表记录
class Publish(models.Model): # id如果不写,会自动生成,名字叫nid,并且自增 id = models.AutoField(primary_key=True) name = models.CharField(max_length=32) addr = models.CharField(max_length=64) email = models.EmailField() class Author(models.Model): id = models.AutoField(primary_key=True) name = models.CharField(max_length=32) # 数字类型 sex = models.IntegerField() # to='AuthorDetail' 加引号,这个表能找到就可以,不用引号,类必须在上面定义 authordetail = models.OneToOneField(to='AuthorDetail', to_field='id') def __str__(self): return self.name class AuthorDetail(models.Model): id = models.AutoField(primary_key=True) phone = models.CharField(max_length=32) addr = models.CharField(max_length=64) class Book(models.Model): id = models.AutoField(primary_key=True) name = models.CharField(max_length=32) price = models.DecimalField(max_digits=5, decimal_places=2) publish = models.ForeignKey(to=Publish, to_field='id') authors = models.ManyToManyField(to=Author) def __str__(self): return self.name