MySQL：Select 一个表中的多个值基于另一个表中的多个值

Question

I would like to return all the reports that are about each of these regions, that belong to a macroregion...我想返回所有关于这些区域的所有报告，属于一个宏观区域......

I would like to somehow我想以某种方式

SELECT DISTINCT report FROM reports WHERE region = 
(SELECT distinct region from macroregions where macroregion = 'Africa')

The regions in the macroregion are Sahara, West Africa, Tropical Africa,... etc宏观区域的区域是撒哈拉沙漠、西非、热带非洲等

Although this is impossible since it the subquery would return multiple results.尽管这是不可能的，因为子查询将返回多个结果。

Answer 1

SELECT DISTINCT report FROM reports WHERE 
region IN 
(SELECT distinct region from macroregions where macroregion = 'Africa')

Maybe you missed IN operator也许你错过了IN运算符

Answer 2

This should get you what you need:这应该可以满足您的需求：

SELECT 
    r.report
FROM
    reports r
INNER JOIN
    macroregions m ON 
        m.region = r.region
        AND 
        m.macroregion = 'Africa'

This is all of the reports associated to regions associated to the macroregion 'Africa'.这是与宏观区域“非洲”相关的区域的所有报告。