Question

我有这个查询

select last_name,job_id,department_id
from empl_demo
where (department_id) in 
(select department_id
from departments
where department_id=60);

我的问题是如何显示＆＃34; department_name＆＃34;从部门表？例如：

select last_name,job_id,department_id,department_name
from empl_demo, departments;

但是它符合我的条件

感谢

Answer 1

似乎department_id是两个表的共同属性。因此，请尝试使用JOINS，如：

select A.last_name, A.job_id, B.department_id, B.department_name
from empl_demo A join departments B
on A.department_id=B.department_id
where B.department_id=60;

如果您想使用子查询，请尝试：

select A.last_name, A.job_id, B.department_id, B.department_name
from (select * from empl_demo where department_id=60) A join 
(select * from departments where department_id=60) B
on A.department_id=B.department_id;

Answer 2

经典INNER加入，你真的需要阅读一些基础知识SQL课程（https://www.w3schools.com/sql/），例如。

SELECT e_d.last_name,
   e_d.job_id,
  e_d.department_id,
  d.department_name
FROM empl_demo e_d
INNER JOIN departments d on d.department_id = e_d.department_id
where department_id=60

在外部查询中显示department_name - sql

2 个答案: