Django:链接 filter() 函数是否会产生与使用多个 kwargs 相同的 SQL？

Question

在 Django 中，以下两个片段是否产生相同的底层 SQL 查询？

qs = MyModel.objects.filter(group=1, type=2) 

和

qs = MyModel.objects.filter(group=1).filter(type=2) 

Answer 1

这实际上取决于是否存在连接或跨区查找，尤其是通过 M2M 关系。例如

>>> print User.objects.filter(groups__gt=1).filter(groups__lt=2).query
SELECT "auth_user"."id", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."password", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."is_superuser", "auth_user"."last_login", "auth_user"."date_joined" FROM "auth_user" INNER JOIN "auth_user_groups" ON ("auth_user"."id" = "auth_user_groups"."user_id") INNER JOIN "auth_user_groups" T4 ON ("auth_user"."id" = T4."user_id") WHERE ("auth_user_groups"."group_id" > 1  AND T4."group_id" < 2 )

>>> print User.objects.filter(groups__gt=1, groups__lt=2).query
SELECT "auth_user"."id", "auth_user"."username", "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", "auth_user"."password", "auth_user"."is_staff", "auth_user"."is_active", "auth_user"."is_superuser", "auth_user"."last_login", "auth_user"."date_joined" FROM "auth_user" INNER JOIN "auth_user_groups" ON ("auth_user"."id" = "auth_user_groups"."user_id") WHERE ("auth_user_groups"."group_id" < 2  AND "auth_user_groups"."group_id" > 1 )