Django 模型查询使用连接

Question

我想让查询按照sql：

sql_str = '''
    select * from luckydraw_winner W
    inner join luckydraw_prizeverificationcodesmslog L on W.id =L.winner_id
    where W.lucky_draw_id = %s
    limit 10
'''

型号：

class Winner(models.Model):
    lucky_draw = models.ForeignKey(LuckyDraw)
    participation = models.ForeignKey(Participation)
    prize = models.ForeignKey(Prize)
    mobile_number = models.CharField(max_length=15, null=True, default = None)

class PrizeVerificationCodeSMSLog(models.Model):
    winner = models.ForeignKey(Winner)
    mobile_number = models.CharField(max_length=15, db_index=True)
    created_on = models.DateTimeField(auto_now_add=True)

因为mobile_number并不总是填写Winner模型，所以我想要的是一个有手机号码或收到短信的获胜者。所以必须加入PrizeVerificationCodeSMSLog才能达到我的目的。
只有赢家很简单：

winners = models.Winner.objects.filter(lucky_draw_id=id).order_by('-created_on')[:10]

但我不知道可以添加什么过滤器来加入PrizeVerificationCodeSMSLog。

---

我终于明白如何在django中检索我想要的数据了。

如果您想让模型A 受另一个模型B 的限制，该模型具有A 的外键，请不要尝试使用filter()。因为A 不知道B，但B 知道A！只需检索A 基B。

Answer 1

试试

logs = PrizeVerificationCodeSMSLog.objects.filter(winner__lucky_draw_id=id).order_by('-created_on')
winners = logs.select_related("winner")[:10]

这会生成以下查询

SELECT "prizeverificationcodesmslog"."id", "prizeverificationcodesmslog"."winner_id", 
    "prizeverificationcodesmslog"."mobile_number", "prizeverificationcodesmslog"."created_on", 
    "winner"."id", "winner"."lucky_draw_id", "winner"."participation_id", 
    "winner"."prize_id", "winner"."mobile_number" 
FROM "prizeverificationcodesmslog" 
INNER JOIN "winner" ON ("prizeverificationcodesmslog"."winner_id" = "winner"."id") 
WHERE "winner"."lucky_draw_id" = 1  
ORDER BY "prizeverificationcodesmslog"."created_on" 
DESC LIMIT 10;

我不确定您的要求是什么，但您可能希望按 Max PrizeVerificationCodeSMSLog 汇总

见https://docs.djangoproject.com/en/1.5/topics/db/aggregation/