sql - 嵌套 SQL 计数

Question

我有两个表，成员和国家，我想要做的是找到所有没有成员的国家。我有点迷茫，这是我最好的猜测，但它不起作用:

SELECT CountryID
FROM Country 
WHERE (SELECT COUNT(MemberID) FROM Member WHERE PrCountryID = CountryID) = 0

任何帮助将不胜感激。

新杰基

Answer 1

尝试使用 not exists条款:

SELECT C.CountryID
FROM Country C
WHERE not exists(SELECT 1 FROM Member M WHERE M.PrCountryID = C.CountryID)