}
	return res, true
}

func dropRune(text string) (res string, ok bool) {
	r := []rune(text)
	if len(r) == 0 {
		return "", false
	}
	return string(r[1:]), true
}

func evalSQLSubstring(s string, startIdx, length int) (res string, err error) {
	rs := []rune(s)

	// According to s3 document, if startIdx < 1, it is set to 1.
	if startIdx < 1 {
		startIdx = 1
	}

		}
		length = int(lenInt)
		if length < 0 {
			err := fmt.Errorf("Negative length argument in %s", sqlFnSubstring)
			return nil, errIncorrectSQLFunctionArgumentType(err)
		}
	}

	res, err := evalSQLSubstring(s, int(startIdx), length)
	return FromString(res), err
}

func handleSQLTrim(r Record, e *TrimFunc, tableAlias string) (res *Value, err error) {
	chars := ""
	ok := false
	if e.TrimChars != nil {