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11 lines
624 B
11 lines
624 B
6 years ago
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class AddUniqIndexToCourseMember < ActiveRecord::Migration[5.2]
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def change
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# sql = %Q(delete from course_members where (user_id, course_id, role) in
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# (select * from (select user_id, course_id, role from course_members group by user_id, course_id, role having count(*) > 1) a)
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# and id not in (select * from (select min(id) from course_members group by user_id, course_id, role having count(*) > 1 order by id) b))
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# ActiveRecord::Base.connection.execute sql
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#
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# add_index :course_members, [:user_id, :course_id, :role], unique: true, name: "index_user_id_course_id_role"
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end
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end
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