return nil, err
	}
	t, ok := ts.ToTimestamp()
	if !ok {
		return nil, fmt.Errorf("%s() expects a timestamp argument", sqlFnDateAdd)
	}

	return dateAdd(strings.ToUpper(d.DatePart), qty, t)
}

func handleDateDiff(r Record, d *DateDiffFunc, tableAlias string) (*Value, error) {
	tval1, err := d.Timestamp1.evalNode(r, tableAlias)
	if err != nil {
		return nil, err
	}

	TrimChars *PrimaryTerm `parser:"             @@?  "`
	TrimFrom  *PrimaryTerm `parser:"             \"FROM\" )? @@ \")\" "`
}

// DateAddFunc represents the DATE_ADD function
type DateAddFunc struct {
	DatePart  string       `parser:" \"DATE_ADD\" \"(\" @( \"YEAR\":Timeword | \"MONTH\":Timeword | \"DAY\":Timeword | \"HOUR\":Timeword | \"MINUTE\":Timeword | \"SECOND\":Timeword ) \",\""`
	Quantity  *Operand     `parser:" @@ \",\""`