# IN

### Introduction to PostgreSQL IN operator <a href="#introduction-to-postgresql-in-operator" id="introduction-to-postgresql-in-operator"></a>

The `IN` operator allows you to check whether a value matches any value in a list of values.

Here’s the basic syntax of the `IN` operator

```sql
value IN (value1,value2,...)
```

The `IN` operator returns true if the `value` is equal to any value in the list such as `value1` and `value2`. The list of values can be a list of literal values including numbers and strings.

### Using the PostgreSQL IN operator with a list of numbers <a href="#id-1-using-the-postgresql-in-operator-with-a-list-of-numbers" id="id-1-using-the-postgresql-in-operator-with-a-list-of-numbers"></a>

The following example uses the `IN` operator to retrieve information about the film with id 1, 2, and 3

```sql
SELECT film_id, title
FROM film
WHERE film_id in (1, 2, 3);
```

<figure><img src="/files/OPyisU7C8wiHurEVraRC" alt=""><figcaption></figcaption></figure>

The following statement uses the equal (`=`) and `OR` operators instead of the `IN` operator, which is equivalent to the query above.

```sql
SELECT film_id, title
FROM film
WHERE 
  film_id = 1
  OR film_id = 2
  OR film_id = 3;
```

The query that uses the `IN` operator is shorter and more readable than the query that uses equal (`=`) and `OR` operators. Additionally, PostgreSQL executes the query with the `IN` operator much faster than the same query that uses a list of `OR` operators.

### Using the PostgreSQL IN operator with a list of strings <a href="#id-2-using-the-postgresql-in-operator-with-a-list-of-strings" id="id-2-using-the-postgresql-in-operator-with-a-list-of-strings"></a>

The following example uses the `IN` operator to find the actors who have the last name in the list `'Allen'`, `'Chase'`, and `'Davis'`

```sql
SELECT first_name, last_name
FROM actor
WHERE last_name IN ('Allen', 'Chase', 'Davis')
ORDER BY last_name;
```

<figure><img src="/files/6BoAkYcWU1Klgn9qkLNd" alt=""><figcaption></figcaption></figure>

### Using the PostgreSQL IN operator with a list of dates <a href="#id-3-using-the-postgresql-in-operator-with-a-list-of-dates" id="id-3-using-the-postgresql-in-operator-with-a-list-of-dates"></a>

The following statement uses the IN operator to find payments whose payment dates are in a list of dates: `2007-02-15` and `2007-02-16`

<pre class="language-sql"><code class="lang-sql"><strong>SELECT payment_id, amount, payment_date
</strong>FROM payment
WHERE payment_date::date IN ('2007-02-15', '2007-02-16');
</code></pre>

<figure><img src="/files/CPX0no9HWzZYu2Do9SwA" alt=""><figcaption></figcaption></figure>

### PostgreSQL NOT IN operator <a href="#postgresql-not-in-operator" id="postgresql-not-in-operator"></a>

To negate the `IN` operator, you use the `NOT IN` operator. Here’s the basic syntax of the `NOT IN` operator

```sql
value NOT IN (value1, value2, ...)
```

The `NOT IN` operator returns `true` if the `value` is not equal to any value in the list such as `value1` and `value2`; otherwise, the `NOT IN` operator returns `false`.

The `NOT IN` operator is equivalent to a combination of multiple boolean expressions with the [AND operators](/database-engineering/filtering-data/and-operator.md)

```sql
value <> value1 AND value <> value2 AND ...
```

The following example uses the `NOT IN` operator to retrieve films whose id is not 1, 2, or 3,

```sql
SELECT
  film_id,
  title
FROM
  film
WHERE
  film_id NOT IN (1, 2, 3)
ORDER BY
  film_id;
```

Output:&#x20;

```
film_id |            title
---------+-----------------------------
       4 | Affair Prejudice
       5 | African Egg
       6 | Agent Truman
       7 | Airplane Sierra
       8 | Airport Pollock
...
```

The following query retrieves the same set of data but uses the not-equal (`<>`) and `AND` operators

```sql
SELECT
  film_id,
  title
FROM
  film
WHERE
  film_id <> 1
  AND film_id <> 2
  AND film_id <> 3
ORDER BY
  film_id;
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://courses.parottasalna.com/database-engineering/filtering-data/in.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.