# Employees With Missing Information Problem

## Description

LeetCode Problem 1965.

Table: Employees

``````1
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+-------------+---------+
| 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

``````1
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+-------------+---------+
| 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:

``````1
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Employees table:
+-------------+----------+
| employee_id | name     |
+-------------+----------+
| 2           | Crew     |
| 4           | Haven    |
| 5           | Kristian |
+-------------+----------+
Salaries table:
+-------------+--------+
| employee_id | salary |
+-------------+--------+
| 5           | 76071  |
| 1           | 22517  |
| 4           | 63539  |
+-------------+--------+

Result table:
+-------------+
| employee_id |
+-------------+
| 1           |
| 2           |
+-------------+

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.
``````

## MySQL Solution

``````1
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select employee_id
from (select employee_id from Employees
union all
select employee_id from Salaries) temp
group by 1
having count(*) = 1
order by 1
``````