问要排除重写值的LINQ查询？

EN

var defaultGroup = techniqueGroups
   .Where(grp => grp.Key.Equals("Default", StringComparison.InvariantCultureIgnoreCase))
   .Aggregate(overridesGroup,
      (overrides, defaults) => {
         var settings = new List<TechniqueSetting>();
         foreach (var setting in defaults) {
            if (overrides.Any(o => o.SettingKey.Key == setting.SettingKey.Key)) {
               continue;
            }

            settings.Add(setting);

         }

         return settings.GroupBy(s => s.Override).First();
      },
      setting => setting);

  internal static IEnumerable<TSource> Exclude<TSource>(this IEnumerable<TSource> Source, Func<TSource, bool> Selector) {
     foreach (var item in Source) {
        if (!Selector(item)) {
           yield return item;
        }
     }
  }  

  internal static IEnumerable<TResult> ReplaceWith<TSource1, TSource2, TResult>(this IEnumerable<TSource1> Source1,
     Func<TSource1, TResult> Source1Result,
     IEnumerable<TSource2> Source2,
     Func<TSource1, IEnumerable<TSource2>, TResult> Selector) {

     foreach (var item in Source1) {
        var replaceWith = Selector(item, Source2);

        if (replaceWith == null) {
           yield return Source1Result(item);
           continue;
        }

        yield return replaceWith;
     }
  }

     var settings = _repository.Settings
        .ReplaceWith(s => s.SettingKeyValue,
           _repository.SettingOverrides.Where(o => o.OverrideName == overrideName),
           (s, overrides) => overrides.Where(o => o.Setting == s)
              .Select(o => o.SettingKeyValueOverride)
              .FirstOrDefault())
        .ToList();

    void Main()
    {

        // Create Tables and Initialize values
        // ***********************************
        var techniqueSettings = new List<TechniqueSettings>();
        techniqueSettings.Add(new TechniqueSettings { Id = 1, Override = "Default", SettingKeyId = 3, Technique="BAZ"});
        techniqueSettings.Add(new TechniqueSettings { Id = 2, Override = "Default", SettingKeyId = 4, Technique="BAZ"});
        techniqueSettings.Add(new TechniqueSettings { Id = 3, Override = "FOO", SettingKeyId = 7, Technique="BAZ"});
        techniqueSettings.Add(new TechniqueSettings { Id = 4, Override = "FOO", SettingKeyId = 8, Technique="BAZ"});    

        var imageSettingOverrides = new List<ImageSettingOverrides>();
        imageSettingOverrides.Add(new ImageSettingOverrides {SettingId = 1, ImageId=1, Override=null } );
        imageSettingOverrides.Add(new ImageSettingOverrides {SettingId = 2, ImageId=1, Override="FOO" } );
        imageSettingOverrides.Add(new ImageSettingOverrides {SettingId = 3, ImageId=1, Override="FOO" } );

        var settingKeyValues = new List<SettingKeyValues>();
        settingKeyValues.Add(new SettingKeyValues {Id = 4, Setting="Wait", Value=1000 } );
        settingKeyValues.Add(new SettingKeyValues {Id = 7, Setting="Wait", Value=10000 } );


        int myImageId = 1;
        string myOverride = "FOO";
        string myTechnique = "BAZ";

        var results = from iso in imageSettingOverrides
                join ts in techniqueSettings on iso.SettingId equals ts.Id
                join skv in settingKeyValues on ts.SettingKeyId equals skv.Id
                where iso.ImageId == myImageId &&
                    //iso.Override.Equals(myOverride,StringComparison.InvariantCultureIgnoreCase)  &&
                    ts.Override.Equals(myOverride,StringComparison.InvariantCultureIgnoreCase)  &&
                    ts.Technique.Equals(myTechnique, StringComparison.InvariantCultureIgnoreCase) 
                select new {
                    ImageId = iso.ImageId,
                    Override = ts.Override,
                    Value = skv.Value
                };


        results.Dump();
    }

    // Define other methods and classes here
    public class ImageSettingOverrides
    {
        public int SettingId {get; set;}
        public int ImageId {get; set;}
        public string Override {get; set;}
    }

    public class TechniqueSettings
    {
        public int Id {get; set;}
        public string Override {get; set;}
        public int SettingKeyId {get; set;}
        public string Technique { get; set;}
    }

    public class SettingKeyValues
    {
        public int Id {get; set;}
        public String Setting {get; set;}
        public int Value {get; set;}
    }

//I'm assuming these are your variables for each IQueryable
IQueryable<TechniqueSetting> techniqueSettings;
IQueryable<ImageSettingOverride> imageSettingOverrides;
IQueryable<SettingKeyValue> settingKeyValues;

var OverridesName = "FOO";
var TechniqueName = "BAZ";

IQueryable<TechniqueSetting> tSettings;
if (OverridesName.Equals("Default", StringComparison.InvariantCultureIgnoreCase))
{
    // Get a list of TechniqueSettings that have this name and are default
    tSettings = techniqueSettings.Where(t => t.Override == OverridesName && t.Technique == TechniqueName);
}
else
{
    // Get a list of TechniqueSettings Id that are overridden 
    //  The ImageSettingOverrides have the same override 
    var overriddenIDs = techniqueSettings.Where(t => t.Technique == TechniqueName && t.Override == "Default")
                                         .Join(
                                             imageSettingOverrides.Where(
                                                 iSettingsOverrides =>
                                                 iSettingsOverrides.Override == OverridesName),
                                             tSetting => tSetting.SettingKeyId,
                                             iSettings => iSettings.TechniqueSettingsId,
                                             (tSetting, iSettingsOverrides) => tSetting.Id);

    // Get a list of techniqueSettings that match the override and TechniqueName but are not part of the overriden IDs
    tSettings =
        techniqueSettings.Where(
            t =>
            t.Technique == TechniqueName && !overriddenIDs.Contains(t.Id) &&
            (t.Override == OverridesName || t.Override == "Default"));
}

// From expected results seems you just want techniqueSettings and that's what would be in techniqueSettings right now.
// If you want a list of SettingKeyValues (which is what is stated in the questions we just need to join them in now)
var settings = tSettings.Join(settingKeyValues, tSetting => tSetting.SettingKeyId,
                              sKeyValues => sKeyValues.Id, (tSetting, sKeyValues) => sKeyValues)
                        .Distinct();