public override SqlString ToSqlString(ICriteria criteria, ICriteriaQuery criteriaQuery, IDictionary<string, IFilter> enabledFilters)
		{
			ISessionFactoryImplementor factory = criteriaQuery.Factory;

			var innerQuery = new CriteriaQueryTranslator(
				factory,
				criteriaImpl, //implicit polymorphism not supported (would need a union)
				criteriaImpl.EntityOrClassName,
				criteriaQuery.GenerateSQLAlias(),
				criteriaQuery);

			types = innerQuery.HasProjection ? innerQuery.ProjectedTypes : null;

			if (innerQuery.HasProjection == false)
			{
				throw new QueryException("Cannot use subqueries on a criteria without a projection.");
			}

			IOuterJoinLoadable persister = (IOuterJoinLoadable) factory.GetEntityPersister(criteriaImpl.EntityOrClassName);

			//patch to generate joins on subqueries
			//stolen from CriteriaLoader
			CriteriaJoinWalker walker =
				new CriteriaJoinWalker(persister, innerQuery, factory, criteriaImpl, criteriaImpl.EntityOrClassName, enabledFilters);

			parameters = innerQuery.GetQueryParameters(); // parameters can be inferred only after initialize the walker

			SqlString sql = walker.SqlString;

			if (criteriaImpl.FirstResult != 0 || criteriaImpl.MaxResults != RowSelection.NoValue)
			{
				int? offset = Loader.Loader.GetOffsetUsingDialect(parameters.RowSelection, factory.Dialect);
				int? limit = Loader.Loader.GetLimitUsingDialect(parameters.RowSelection, factory.Dialect);
				Parameter offsetParameter = offset.HasValue ? innerQuery.CreateSkipParameter(offset.Value) : null;
				Parameter limitParameter = limit.HasValue ? innerQuery.CreateTakeParameter(limit.Value) : null;
				sql = factory.Dialect.GetLimitString(sql, offset, limit, offsetParameter, limitParameter);
			}

			SqlStringBuilder buf = new SqlStringBuilder().Add(ToLeftSqlString(criteria, criteriaQuery));
			if (op != null)
			{
				buf.Add(" ").Add(op).Add(" ");
			}

			if (quantifier != null && prefixOp)
			{
				buf.Add(quantifier).Add(" ");
			}

			buf.Add("(").Add(sql).Add(")");

			if (quantifier != null && prefixOp == false)
			{
				buf.Add(" ").Add(quantifier);
			}

			return buf.ToSqlString();
		}