text: from django.db import models
  
  sex = [
      ('M', 'male'),
      ('F', 'female'),
  ]
  
  class Employee(models.Model):
      ssn = models.AutoField(primary_key=True)
      fname = models.CharField('First Name', max_length=150)
      minit = models.CharField('Middle Name', max_length=150)
      lname = models.CharField('Last Name', max_length=150)
      bdate = models.DateField('birth date')
      address = models.CharField(max_length=200)
      gender = models.CharField(max_length=10, choices=sex, default=1)
      salary = models.FloatField()
      super_ssn = models.ForeignKey('self', on_delete=models.CASCADE, blank=True, null=True)
      dno = models.ForeignKey("department.Department", verbose_name="Department Number", on_delete=models.SET_NULL, blank=True, null=True)
  
      def __str__(self):
          return self.fname + self.lname
  