public void linq2db_Expression() { var param = TestEnum1.Value1; var l = new List <NullableTestTable1>(); System.Linq.Expressions.Expression <Func <IEnumerable <NullableTestTable1> > > e = () => l .Where(r => r.Id == RID && r.TestField == TestEnum1.Value2) .Select(r => new NullableTestTable1 { Id = r.Id, TestField = param }); var compiled = e.CompileFast(true); compiled(); }