Question

我正在使用django创建一个简单的结果处理系统。我做了这个课：

class Course(models.Model):
    Course_Code = models.CharField(max_length=50,unique=True,primary_key = True)
    Course_Name = models.CharField(max_length=50)
    Dept = models.CharField(max_length=50)
    Credit_Lecture = models.IntegerField()
    Credit_Tutorial = models.IntegerField()
    Credit_Practical = models.IntegerField()
    Max_Marks_MidTerm = models.IntegerField()
    Max_Marks_Theory = models.IntegerField()
    Max_Marks_Pr = models.IntegerField()

现在我想创建一个新列，用于存储课程的总学分值，即：

Credit_Total = Credit_Lecture + Credit_Tutorial + Credit_Practical

我该怎么办？我发现了以下可能性但失败了：

Total_Credit =Credit_Lec + Credit_Tut + Credit_Pr

Total_credit = SELECT CAST(Credit_lec AS VARCHAR(255)) AS credit_lec FROM Course;

Answer 1

您还可以在模型中创建一个属性，如

@property
def total_credit(self):
    tc = self.Credit_Lecture + self.Credit_Tutorial + self.Credit_Practical
    return tc

将其添加到Courses类

中

无论您希望在何处显示此信息，您都可以依赖它。

tc = Course.total_credit

如何在django sqlite models.py文件中从现有列创建新列？

1 个答案: