删除多余的数据

db/migrate/20190703090511_add_index_for_shixun_services.rb

@@ -1,5 +1,9 @@
 class AddIndexForShixunServices < ActiveRecord::Migration[5.2]
   def change
+    sql = %Q(delete from shixun_service_configs where (shixun_id, mirror_repository_id) in
+            (select * from (select shixun_id, mirror_repository_id from shixun_service_configs group by shixun_id, mirror_repository_id having count(*) > 1) a)
+            and id not in (select * from (select min(id) from shixun_service_configs group by shixun_id, mirror_repository_id having count(*) > 1 order by id) b))
+    ActiveRecord::Base.connection.execute sql
     add_index :shixun_service_configs, [:shixun_id, :mirror_repository_id], unique: true, name: "shixun_id_mirror_id_unique"
   end
 end