django模型三

表关系的实现

•  一对一
  • 　

     1 from django.db import models
     2 
     3 # Create your models here.
     4 
     5 class Account(models.Model):
     6     username = models.CharField(max_length=20)
     7     password = models.CharField(max_length=50)
     8     phonenum = models.CharField(max_length=20, default='')
     9     c_time = models.DateTimeField(auto_now_add=True,)  # 创建时间
    10 
    11 
    12 class Detail(models.Model):
    13     num = models.CharField(max_length=10, default='')
    14     hobby = models.CharField(max_length=10, default='')
    15     account = models.OneToOneField('Account', on_delete=models.CASCADE)

    在对应表里面新加字段，使用models.OnToOneField方法，第一个参数接收对应表的类的字符串，第二个设置关联，当被关联的表被删除的时候，该表也会被删除
  • 使用:
    • 用Detail查询username　　
    • Detail.objects.filter(num="3").first().account.username
• 一对多

  •  1 from django.db import models
     2 
     3 # Create your models here.
     4 
     5 class Account(models.Model):
     6     username = models.CharField(max_length=20)
     7     password = models.CharField(max_length=50)
     8     phonenum = models.CharField(max_length=20, default='')
     9     c_time = models.DateTimeField(auto_now_add=True,)  # 创建时间
    10     many = models.ForeignKey('Many', on_delete=models.SET_NULL, null=True)
    11 
    12 
    13 class Detail(models.Model):
    14     num = models.CharField(max_length=10, default='')
    15     hobby = models.CharField(max_length=10, default='')
    16     account = models.OneToOneField('Account', on_delete=models.CASCADE)
    17 
    18 
    19 class Many(models.Model):
    20     num = models.CharField(max_length=10, default='')
    21     hobby = models.CharField(max_length=10, default='')

    在对应的表里设置主键(model.ForeignKey)