if !ok {
		return nil, fmt.Errorf("%s() expects two timestamp arguments", sqlFnDateDiff)
	}

	return dateDiff(strings.ToUpper(d.DatePart), ts1, ts2)
}

func handleUTCNow() (*Value, error) {
	return FromTimestamp(time.Now().UTC()), nil
}

func handleSQLSubstring(r Record, e *SubstringFunc, tableAlias string) (val *Value, err error) {
	// Both forms `SUBSTRING('abc' FROM 2 FOR 1)` and
	// SUBSTRING('abc', 2, 1) are supported.