SELECT
Continent,
COUNT(*) AS CountriesCount
FROM country
GROUP BY Continent
HAVING COUNT(*) > 20
| Continent | CountriesCount |
| Asia | 51 |
| Europe | 46 |
| North America | 37 |
| Africa | 58 |
| Oceania | 28 |
| HAVING 与 WHERE 很相似。事实上，前面学过的各种 WHERE 条件都可以用在 HAVING 上。区别只有一个：WHERE 过滤行，HAVING 过滤分组。 |