您可以使用case表达式来决定何时添加标签，从而实现更多控制：

SELECT CASE WHEN CITY.COUNTRY IS NULL
       THEN 'Summary-total:' ELSE CITY.COUNTRY END AS VISITED_COUNTRY, 
       CASE WHEN CITY.COUNTRY IS NOT NULL AND CITY.NAME IS NULL
       THEN 'Summary-country:' ELSE CITY.NAME END AS CITY, 
       CASE WHEN CITY.COUNTRY IS NOT NULL AND CITY.NAME IS NOT NULL AND ACCOMMODATIONTYPE.NAME IS NULL
       THEN 'Summary-city:' ELSE ACCOMMODATIONTYPE.NAME END AS TYPE,
       SUM(VISIT.NUMBER_OF_VISITORS) VISITORS, 
       SUM(VISIT.PROFIT) AS PROFIT
FROM VISIT
       JOIN CITY ON VISIT.ID_CITY = CITY.ID_CITY 
       JOIN ACCOMMODATIONTYPE ON VISIT.ID_TYPE = ACCOMMODATIONTYPE.ID_TYPE
GROUP BY 
    ROLLUP(CITY.COUNTRY, CITY.NAME, ACCOMMODATIONTYPE.NAME) 
ORDER BY 
    VISITED_COUNTRY, CITY, TYPE;

如果您愿意，也可以将大小写表达式与NVL或COALESCE混合使用以简化它：

SELECT COALESCE(CITY.COUNTRY, 'Summary-total:') AS VISITED_COUNTRY, 
       CASE WHEN CITY.COUNTRY IS NOT NULL
       THEN COALESCE(CITY.NAME, 'Summary-country:') END AS CITY, 
       CASE WHEN CITY.COUNTRY IS NOT NULL AND CITY.NAME IS NOT NULL
       THEN COALESCE(ACCOMMODATIONTYPE.NAME, 'Summary-city:') END AS TYPE,
       SUM(VISIT.NUMBER_OF_VISITORS) VISITORS, 
       SUM(VISIT.PROFIT) AS PROFIT
FROM VISIT
       JOIN CITY ON VISIT.ID_CITY = CITY.ID_CITY 
       JOIN ACCOMMODATIONTYPE ON VISIT.ID_TYPE = ACCOMMODATIONTYPE.ID_TYPE
GROUP BY 
    ROLLUP(CITY.COUNTRY, CITY.NAME, ACCOMMODATIONTYPE.NAME) 
ORDER BY 
    VISITED_COUNTRY, CITY, TYPE;

fiddle
它是主题“SQLforOLAP”中OracleSQL学习任务
在这种情况下，可能更合适的方法是查看分组ID，并使用它们来确定何时应用标签，就像@serg建议的那样。如果你正在学习一些东西，那么任务通常希望你使用你最近被介绍过的东西。
grouping()的类似方法：

SELECT CASE WHEN GROUPING(CITY.COUNTRY) = 1
       THEN 'Summary-total:' ELSE CITY.COUNTRY END AS VISITED_COUNTRY, 
       CASE WHEN GROUPING(CITY.COUNTRY) = 0 AND GROUPING(CITY.NAME) = 1
       THEN 'Summary-country:' ELSE CITY.NAME END AS CITY, 
       CASE WHEN GROUPING(CITY.COUNTRY) = 0 AND GROUPING(CITY.NAME) = 0 AND GROUPING(ACCOMMODATIONTYPE.NAME) = 1
       THEN 'Summary-city:' ELSE ACCOMMODATIONTYPE.NAME END AS TYPE,
       SUM(VISIT.NUMBER_OF_VISITORS) VISITORS, 
       SUM(VISIT.PROFIT) AS PROFIT
FROM VISIT
       JOIN CITY ON VISIT.ID_CITY = CITY.ID_CITY 
       JOIN ACCOMMODATIONTYPE ON VISIT.ID_TYPE = ACCOMMODATIONTYPE.ID_TYPE
GROUP BY 
    ROLLUP(CITY.COUNTRY, CITY.NAME, ACCOMMODATIONTYPE.NAME) 
ORDER BY 
    VISITED_COUNTRY, CITY, TYPE;

fiddle