将列表转换为元组在Postgres中可以正常工作，尽管在sqlite3下相同的代码DatabaseError: near "?": Syntax error也会失败，因此看来这是后端特定的。您的代码行将变为：
results = MMCode.objects.raw('select assigner, assignee from mm_code where date between %s and %s and country_code in %s',[fromdate,todate,tuple(region)])
我在一个干净的Django 1.5.1项目上用bar / models.py中的以下代码对此进行了测试：
from django.db import models
class MMCode(models.Model):
assigner = models.CharField(max_length=100)
assignee = models.CharField(max_length=100)
date = models.DateField()
country_code = models.CharField(max_length=2)
然后在外壳上：
>>> from datetime import date
>>> from bar.models import MMCode
>>>
>>> regions = ['US', 'CA', 'UK']
>>> fromdate = date.today()
>>> todate = date.today()
>>>
>>> results = MMCode.objects.raw('select id, assigner, assignee from bar_mmcode where date between %s and %s and country_code in %s',[fromdate,todate,tuple(regions)])
>>> list(results)
[]
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