public static IQueryable func(this DwhContext context, string table)
        {
            var type = context.GetType();
            var tab = type.GetProperty(table);
            var prop = tab.GetValue(context) as IQueryable;
            var e = prop.Expression;
            var t = prop.ElementType;
            var expr = MakeExpression(t);
            var qt = typeof(Queryable).GetMethods()
                .FirstOrDefault(x => x.Name == "Where" && x.GetParameters().Length == 2)
                .MakeGenericMethod(t);
            var res = Expression.Call(qt,e, expr);
            var tmp = Expression.Lambda(res).Compile().DynamicInvoke();
            return tmp as IQueryable;
        }
        static Expression MakeExpression(Type t)
        {
            var par = Expression.Parameter(t, "x");
            var id = t.GetProperty("Id");
            var left = Expression.MakeMemberAccess(par, id);
            var rigth = Expression.Constant(5);
            var body = Expression.Equal(left, rigth);
            var lambda = Expression.Lambda(body, par);
            return lambda;
        }