我们如何在 Django 中加入两个表？

Question

Is it possible to join two models(tables) based on a common key(foreign key) in Django? If so, please explain it with an example. I went through the Django documentation for this. But I landed on how to perform raw SQL queries in django.

Thanks

Answer 1

Here is an example from Django Documentation :

from django.db import models

class Reporter(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)
    email = models.EmailField()

    def __str__(self):
        return "%s %s" % (self.first_name, self.last_name)

class Article(models.Model):
    headline = models.CharField(max_length=100)
    pub_date = models.DateField()
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    def __str__(self):
        return self.headline

    class Meta:
        ordering = ('headline',)

With this example you can easily reach article's reporter by:

print(article.reporter.firstname, article.reporter.last_name)

But if you consist of running raw SQL queries, here is an example (more details on Django documentation ):

from django.db import connection

def my_custom_sql(self):
    with connection.cursor() as cursor:
        cursor.execute("UPDATE bar SET foo = 1 WHERE baz = %s", [self.baz])
        cursor.execute("SELECT foo FROM bar WHERE baz = %s", [self.baz])
        row = cursor.fetchone()

    return row