我不太喜欢sql，我有以下问题。我正在使用mysql
我必须更改此查询：
SELECT
USR.id AS hq_user_id,
USR.local_user_id,
LCZ.id AS localization_id,
LCZ.description AS description,
LCZ_COUNTRY_LEVEL.id AS country_id,
LCZ_COUNTRY_LEVEL.description AS country_description
FROM Localization AS LCZ
INNER JOIN User AS USR
ON USR.localization_id = LCZ.id
INNER JOIN Localization AS LCZ_COUNTRY_LEVEL
ON LCZ_COUNTRY_LEVEL.country_id = LCZ.country_id
WHERE USR.local_user_id = 999正在删除第二个内部联接：
INNER JOIN Localization AS LCZ_COUNTRY_LEVEL
ON LCZ_COUNTRY_LEVEL.country_id = LCZ.country_id并将其替换为我编写的另一个查询的输出：
SELECT
LCZ2.id AS localization_id_nation_level,
LCZ2.country_id AS country_id
FROM Localization AS LCZ2
WHERE
LCZ2.region_id is null
AND LCZ2.province_id is null
AND LCZ2.city_id is null
AND LCZ2.district_id is null
AND LCZ2.town_id is null
AND LCZ2.village_id is null联接条件应为：
lcz.country\u id应与第二个查询中返回的lcz2.country\u id字段相同。
我该怎么做？
1条答案
按热度按时间2q5ifsrm1#
而不是加入
Localization表中，联接到所需的子查询。这里没什么魔力。只需将子查询用括号括起来，给它一个别名（我使用t，然后在连接条件中使用该别名。