leetcode-problemset/leetcode/problem/employees-with-missing-information.html

<p>Table: <code>Employees</code></p>

<pre>
+-------------+---------+
| 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.
</pre>

<p>&nbsp;</p>

<p>Table: <code>Salaries</code></p>

<pre>
+-------------+---------+
| 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.
</pre>

<p>&nbsp;</p>

<p>Write an SQL query to report the IDs of all the employees with <strong>missing information</strong>. The information of an employee is missing if:</p>

<ul>
	<li>The employee&#39;s <strong>name</strong> is missing, or</li>
	<li>The employee&#39;s <strong>salary</strong> is missing.</li>
</ul>

<p>Return the result table ordered by <code>employee_id</code> <strong>in ascending order</strong>.</p>

<p>The query result format is in the following example.</p>

<p>&nbsp;</p>
<p><strong>Example 1:</strong></p>

<pre>
<strong>Input:</strong> 
Employees table:
+-------------+----------+
| employee_id | name     |
+-------------+----------+
| 2           | Crew     |
| 4           | Haven    |
| 5           | Kristian |
+-------------+----------+
Salaries table:
+-------------+--------+
| employee_id | salary |
+-------------+--------+
| 5           | 76071  |
| 1           | 22517  |
| 4           | 63539  |
+-------------+--------+
<strong>Output:</strong> 
+-------------+
| employee_id |
+-------------+
| 1           |
| 2           |
+-------------+
<strong>Explanation:</strong> 
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.
</pre>