使用IN（）和强制值的SQL查询

我有一个内部联接查询，它根据联接表中的值获取国家名称：

SELECT DISTINCT countryName, countrySlug
FROM countries AS Country
INNER JOIN countries_networks AS n ON Country.id = n.country_id
AND n.network_id IN ( 6, 7, 8, 9, 14 ) 

但是，我现在需要

选择符合IN（）标准的
，并且必须包含网络2

显然，我不能只将2添加到IN（），因为我需要2是强制性的，至少有一个是其他的

有人能帮忙吗，我觉得这太简单了。
试试这个：

SELECT DISTINCT 
  countryName, 
  countrySlug
FROM countries AS Country
INNER JOIN countries_networks AS n  ON Country.id   = n.country_id
                                   AND n.network_id IN (6, 7, 8, 9, 14) 
WHERE Country.id IN (SELECT id
                     FROM countries_networks 
                     WHERE network_id = 2
                       AND id IS NOT NULL);

这将确保任何选定的国家/地区必须具有
网络id=2
首先，通过将联接替换为
存在
子查询来删除
不同的
。然后，您可以添加另一个子查询来处理额外的需求：

SELECT countryName, countrySlug
FROM countries AS c
WHERE EXISTS
      ( SELECT *
        FROM countries_networks AS n 
        WHERE c.id = n.country_id
          AND n.network_id IN ( 6, 7, 8, 9, 14 )
      )
  AND EXISTS
      ( SELECT *
        FROM countries_networks AS n 
        WHERE c.id = n.country_id
          AND n.network_id = 2
      ) ;

试试这个（双重连接？）：

注：显示的
n.country\u id，n2.country\u id
值仅用于检查结果
只需执行以下操作：

SELECT DISTINCT countryName, countrySlug
FROM countries AS Country
INNER JOIN countries_networks AS n ON Country.id = n.country_id
AND n.network_id=2 And n.network_id IN (2, 6, 7, 8, 9, 14 )

SELECT DISTINCT countryName, countrySlug
FROM countries AS Country
INNER JOIN countries_networks AS n ON Country.id = n.country_id
AND n.network_id=2 And n.network_id IN (2, 6, 7, 8, 9, 14 )