function SubtractDateFromDateAsYearMonth(FirstValue: TDateTime;
      SecondValue: TDateTime; YearMonthIntervalType:
      TEDBYearMonthIntervalType): TEDBYearMonthInterval

 In ElevateDB, year-month intervals are Integer values that represent the number of days that have elapsed between two calendar days. Use the TEDBEngine YearMonthIntervalToSQLStr method to convert a year-month interval into a readable string.