LeetCode（数据库）- 员工的直属部门

Posted 2021-12-25 程序员牧码

题目链接：点击打开链接

题目大意：略。

解题思路：略。

AC 代码

-- 解决方案(1)
select employee_id,department_id from
(select employee_id,department_id,row_number() over(partition by employee_id order by primary_flag desc) rno from employee)
where rno=1

-- 解决方案(2)
SELECT employee_id, department_id
FROM Employee
WHERE primary_flag = 'Y'

UNION

SELECT employee_id, department_id 
FROM Employee
GROUP BY employee_id
HAVING COUNT(*) = 1