Custom Rule Engine in WPF - MVVM

-----------------------------------------------------------------Stored Procedure----------------------------------------------------------------------------------
CREATE PROCEDURE dbo.SelectRules
@screenID INT
AS
	SELECT        CD.ScreenID, CD.ResultText, R.CodeLHS, R.Operator, R.ValueRHS, R.Source,RGR.RuleGroupID, RGR.RuleJoinOperator, RGR.RuleSeqNum, RGGR.RuleGroupJoinOperator, 
                         RGGR.RuleGroupSeqNum, R.RuleDescription
FROM            CountryDetails AS CD INNER JOIN
                         RulesGroupGroupingRelations AS RGGR ON CD.RuleGroupGroupingID = RGGR.RuleGroupGroupingID INNER JOIN
                         RulesGroupRelations AS RGR ON RGGR.RuleGroupID = RGR.RuleGroupID INNER JOIN
                         Rules AS R ON R.RuleID = RGR.RuleID WHERE CD.ScreenID = @screenID 
ORDER BY RGGR.RuleGroupGroupingID, RGGR.RuleGroupSeqNum, RGR.RuleGroupID, RGR.RuleSeqNum