Returns the number of months elapsed between dates or timestamps in
expr1: An DATE or TIMESTAMP expression.
expr2: An expression of the same type as
roundOff: A optional BOOLEAN expression.
expr1 is later than
expr2, the result is positive.
expr2 are on the same day of the month, or both are the last day of the month, time of day is ignored.
Otherwise, the difference is calculated based on 31 days per month, and rounded to 8 digits unless