how to realize count and distinct together?

[yodew]

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[yodew]

I want to execute the below sql:

select count(*) from (SELECT DISTINCT `students_id`, `subject_id`, `school_id`
FROM `user_item_score`
WHERE `deleted` = 0
  AND `score_type` = 2
  AND `score_year` = '') a;

so, how to do with the orm? I try it with Concat and Subquery，but failed.

[vlakius]

Could you please provide your models ?