1965.-employees-with-missing-information.md

1965. Employees With Missing Information

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.

MySQL

Result

Runtime: 417 ms, faster than 98.07% of MySQL online submissions for Employees With Missing Information.

Memory Usage: 0B, less than 100.00% of MySQL online submissions for Employees With Missing Information.

SQL Schema

Create table If Not Exists Employees
(
    employee_id int,
    name        varchar(30)
);

Create table If Not Exists Salaries
(
    employee_id int,
    salary      int
);

Truncate table Employees;

insert into Employees (employee_id, name)
values ('2', 'Crew');

insert into Employees (employee_id, name)
values ('4', 'Haven');

insert into Employees (employee_id, name)
values ('5', 'Kristian');

Truncate table Salaries;

insert into Salaries (employee_id, salary)
values ('5', '76071');

insert into Salaries (employee_id, salary)
values ('1', '22517');

insert into Salaries (employee_id, salary)
values ('4', '63539');

Solution

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