text: from django.db import models
  
  
  class Stock(models.Model):
      id = models.BigAutoField(primary_key=True)
      date = models.DateField()
      ticker_symbol = models.CharField(max_length=5)
      open = models.DecimalField(max_digits=20, decimal_places=5)
      high = models.DecimalField(max_digits=20, decimal_places=5)
      low = models.DecimalField(max_digits=20, decimal_places=5)
      close = models.DecimalField(max_digits=20, decimal_places=5)
      volume = models.IntegerField()
  
      def __str__(self):
          return "Name: <%r> Date: <%r> High: <%.4f> Low: <%.4f>" % (
              self.ticker_symbol,
              str(self.date),
              self.high,
              self.low,
          )
  
  
  class Buy(models.Model):
      id = models.BigAutoField(primary_key=True)
      date = models.DateField()
      ticker_symbol = models.ForeignKey(Stock, on_delete=models.CASCADE)
      volume = models.IntegerField()
  
      def __str__(self):
          return f"Name: {self.ticker_symbol} Date: {str(self.date)} Size: {self.volume}"
  
  
  class Sell(models.Model):
      id = models.BigAutoField(primary_key=True)
      date = models.DateField()
      ticker_symbol = models.ForeignKey(Stock, on_delete=models.CASCADE)
      volume = models.IntegerField()
  
      def __str__(self):
          return f"Name: {self.ticker_symbol} Date: {str(self.date)} Size: {self.volume}"
  