Description
At now, `DateType +/- DayTimeIntervalType()` will convert the DateType to TimestampType, then TimeAdd. When interval type is DayTimeIntervalType(DAY), it can use DateAdd instead of TimeAdd.
At now, `DateType +/- DayTimeIntervalType()` will convert the DateType to TimestampType, then TimeAdd. When interval type is DayTimeIntervalType(DAY), it can use DateAdd instead of TimeAdd.