Ad-Free Sessions
<p>Table: <code>Playback</code></p>

<pre>
+-------------+------+
| Column Name | Type |
+-------------+------+
| session_id  | int  |
| customer_id | int  |
| start_time  | int  |
| end_time    | int  |
+-------------+------+
session_id is the column with unique values for this table.
customer_id is the ID of the customer watching this session.
The session runs during the <strong>inclusive</strong> interval between start_time and end_time.
It is guaranteed that start_time &lt;= end_time and that two sessions for the same customer do not intersect.</pre>

<p>&nbsp;</p>

<p>Table: <code>Ads</code></p>

<pre>
+-------------+------+
| Column Name | Type |
+-------------+------+
| ad_id       | int  |
| customer_id | int  |
| timestamp   | int  |
+-------------+------+
ad_id is the column with unique values for this table.
customer_id is the ID of the customer viewing this ad.
timestamp is the moment of time at which the ad was shown.
</pre>

<p>&nbsp;</p>

<p>Write a solution to report all the sessions that did not get shown any ads.</p>

<p>Return the result table in <strong>any order</strong>.</p>

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

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> 
Playback table:
+------------+-------------+------------+----------+
| session_id | customer_id | start_time | end_time |
+------------+-------------+------------+----------+
| 1          | 1           | 1          | 5        |
| 2          | 1           | 15         | 23       |
| 3          | 2           | 10         | 12       |
| 4          | 2           | 17         | 28       |
| 5          | 2           | 2          | 8        |
+------------+-------------+------------+----------+
Ads table:
+-------+-------------+-----------+
| ad_id | customer_id | timestamp |
+-------+-------------+-----------+
| 1     | 1           | 5         |
| 2     | 2           | 17        |
| 3     | 2           | 20        |
+-------+-------------+-----------+
<strong>Output:</strong> 
+------------+
| session_id |
+------------+
| 2          |
| 3          |
| 5          |
+------------+
<strong>Explanation:</strong> 
The ad with ID 1 was shown to user 1 at time 5 while they were in session 1.
The ad with ID 2 was shown to user 2 at time 17 while they were in session 4.
The ad with ID 3 was shown to user 2 at time 20 while they were in session 4.
We can see that sessions 1 and 4 had at least one ad. Sessions 2, 3, and 5 did not have any ads, so we return them.
</pre>
Database
# Write your MySQL query statement below
SELECT session_id
FROM Playback
WHERE
    session_id NOT IN (
        SELECT session_id
        FROM
            Playback AS p
            JOIN Ads AS a
                ON p.customer_id = a.customer_id AND a.timestamp BETWEEN p.start_time AND p.end_time
    );
