目前试图获取一个组的平均值,但当我尝试执行正确的查询集时,它会抱怨语法不正确
objs = MyModel.objects.filter(...).values('user','value') objs = objs.annotate(sum=Sum('value')) # i've also tried adding `.values('sum')` to the above objs = objs.aggregate(Avg('sum')) # whines here
有没有办法在不放弃sql的情况下执行此操作?所需的sql就是这样的
SELECT AVG(`sum`) as `avg` FROM ( SELECT SUM(`appname_mymodel`.`value`) AS `sum` FROM `appname_mymodel` GROUP BY `appname_mymodel`.`user_id`,`appname_mymodel`.`value` ) as subquery ORDER BY NULL;
不确定django是否适合子查询.
这是错误消息:
ProgrammingError: (1064,"You have an error in your sql Syntax; check the manual that corresponds to your MysqL server version for the right Syntax to use near 'FROM (SELECT SUM(`appname_mymodel`.`value`) AS `sum` FROM `appname_' at line 1")
Django版本 – 1.6.5
MysqL版本 – 5.5
笔记:
>如果我省略了值(分组依据),它可以正常工作(即objs.filter(…).annotate(…).aggregate(…)
>以下示例足以作为完全可重复的示例.
模型:
# Create your models here. class UserProfile(models.Model): name = models.CharField(max_length=200) class OtherFK(models.Model): name = models.CharField(max_length=200) class MyModel(models.Model): # Happens if value is CharField or IntegerField value = models.CharField(max_length=200,blank=True,null=True) date = models.DateField() user = models.ForeignKey(UserProfile) other_fk = models.ForeignKey(OtherFK)
例:
>>> from app_name.models import UserProfile,OtherFK,MyModel >>> up = UserProfile.objects.create(name="test") >>> fk = OtherFK.objects.create(name="test") >>> v1 = MyModel.objects.create(user=up,other_fk=fk,value="12",date="2015-10-01") >>> v2 = MyModel.objects.create(user=up,value="13",date="2015-10-02") >>> from django.db.models import Sum,Avg >>> MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value")).aggregate(Avg('sum')) ProgrammingError: (1064,"You have an error in your sql Syntax; check the manual that corresponds to your MysqL server version for the right Syntax to use near 'FROM (SELECT disTINCT `app_name_mymodel`.`user_id` AS `user_id`,SUM(`app_name_m' at line 1") >>> MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value")) [{'sum': 25.0,'user': 1L}] >>> print MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value")).query SELECT disTINCT `app_name_mymodel`.`user_id`,SUM(`app_name_mymodel`.`value`) AS `sum` FROM `app_name_mymodel` GROUP BY `app_name_mymodel`.`user_id` ORDER BY NULL
解决方法
我认为这就是您所需要的,请在测试下面的一行后给出反馈:
MyModel.objects.filter(...).values('user__id').distinct().annotate(sum=Sum('value')).aggregate(Avg('sum'))