Problem
Table: Employees
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| employee_id | int |
| name | varchar |
+-------------+---------+
employee_id is the primary key for this table.
Each row of this table indicates the name of the employee whose ID is employee_id.
Table: Salaries
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| employee_id | int |
| salary | int |
+-------------+---------+
employee_id is the primary key for this table.
Each row of this table indicates the salary of the employee whose ID is employee_id.
Write an SQL query to report the IDs of all the employees with missing information. The information of an employee is missing if:
The employee's name is missing, or
The employee's salary is missing.
Return the result table ordered by employee_id in ascending order.
The query result format is in the following example.
Example 1:
Input:
Employees table:
+-------------+----------+
| employee_id | name |
+-------------+----------+
| 2 | Crew |
| 4 | Haven |
| 5 | Kristian |
+-------------+----------+
Salaries table:
+-------------+--------+
| employee_id | salary |
+-------------+--------+
| 5 | 76071 |
| 1 | 22517 |
| 4 | 63539 |
+-------------+--------+
Output:
+-------------+
| employee_id |
+-------------+
| 1 |
| 2 |
+-------------+
Explanation:
Employees 1, 2, 4, and 5 are working at this company.
The name of employee 1 is missing.
The salary of employee 2 is missing.
Solution
# Write your MySQL query statement below
select employee_id
from employees
where employee_id not in (select employee_id from salaries)
UNION
select employee_id
from salaries
where employee_id not in (select employee_id from Employees)
order by 1
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).