Contract_Period__c false if ( or( isnull( Contract_End_Date__c), isnull( Contract_Start_Date__c), Contract_End_Date__c < Contract_Start_Date__c), 0, Contract_End_Month_Number__c - Contract_Start_Month_Number__c + 1 ) BlankAsZero 契約期間(月) 18 false 0 false false Number false