Hiearchy를 가지는 Composite Key에 대해 계층을 만드는 LINQ예

LinqHierachyBuildQuery.cs

    public class SeqKeyRepository
    {
        public Dictionary<long, Dictionary<long, Dictionary<long, Dictionary<long, HashSet<long>>>>> FindHierachies()
        {
            return FindAll()
                    .GroupBy(key => key.DeviceId)
                    .ToDictionary(deviceGroup => deviceGroup.Key, deviceGroup =>
                    {
                        return deviceGroup
                            .GroupBy(key => key.SeqId)
                            .ToDictionary(stepGroup => stepGroup.Key, stepGroup =>
                            {
                                return stepGroup
                                    .GroupBy(key => key.RecipeId)
                                    .ToDictionary(recipeGroup => recipeGroup.Key, recipeGroup =>
                                    {
                                        return recipeGroup
                                                .GroupBy(key => key.ModelId)
                                                .ToDictionary(modelGroup => modelGroup.Key, modelGroup =>
                                                {
                                                    return new HashSet<long>(modelGroup.Select(key => key.SeqId));
                                                })
                                            ;
                                    });
                            });
                    })
                ;
        }

        public IEnumerable<SeqKey> FindAll()
        {
            return OpticaDb.Instance
                .Query<SeqKey>("select DEVICE_ID as DeviceId, STEP_ID as StepId, RECIPE_ID as RecipeId, MODEL_ID as ModelId, SEQ_ID as SeqId from SIM_RESULT");
        }
    }

    public class SeqKey
    {
        public long DeviceId { get; set; }
        public long StepId { get; set; }
        public long RecipeId { get; set; }
        public long ModelId { get; set; }
        public long SeqId { get;set; }
    }