选择列不存在于链接表中

Question

我想从主表中选择指定的列，该列不存在于链接表中。但即使id仍然不存在于链接表中，它也会给我一个空行。

SELECT faculty_mt.firstName FROM faculty_mt
INNER JOIN section_settings_lt ON section_settings_lt.adviser_id = faculty_mt.faculty_id
WHERE faculty_mt.faculty_id NOT IN (SELECT adviser_id FROM section_settings_lt);

我尝试从SELECT adviser_id更改为SELECT session_id，但这为我提供了一个存在于我的链接表中的值。

faculty_mt

faculty_id | firstName 15 Daisy 16 Orange

section_settings_lt

section_id | adviser_id | session_id 1 15 1

输出应为：

firstName Orange

Answer 1

你可以试试这个：

SELECT
    faculty_mt.firstName
FROM
    faculty_mt
LEFT JOIN
    section_settings_lt
ON
    section_settings_lt.adviser_id = faculty_mt.faculty_id
WHERE
    section_settings_lt.adviser_id is NULL;