Nhibernate Case SUM

SELECT
ID
SUM(CASE WHEN myProperty = 2 THEN 1 ELSE 0 END) as nbRowWithValueOf2,
SUM(CASE WHEN myProperty = 3 THEN 1 ELSE 0 END) as nbRowWithValueOf3
FROM Foo
GROUP BY ID

queryover = queryover
    .Select(
        Projections.Group<Foo>(c => c.ID),
        Projections.Sum(
            Projections.Conditional(
                Restrictions.Where<Foo>(f => f.myProperty == MyEnum.Two),
                Projections.Constant(),
                Projections.Constant())),
        Projections.Sum(
            Projections.Conditional(
                Restrictions.Where<Foo>(f => f.myProperty == MyEnum.Three),
                Projections.Constant(),
                Projections.Constant())));

生成SQL

SELECT this_.ID as y0_,
       sum((case
              when this_.myProperty = 2 /* @p0 */ then 1 /* @p1 */
              else 0 /* @p2 */
            end))               as y1_,
       sum((case
              when this_.myProperty = 3 /* @p3 */ then 1 /* @p4 */
              else 0 /* @p5 */
            end))               as y2_
FROM   [Foo] this_
GROUP  BY this_.ID