Working with IN in MySQL

Intro

MySql provides the IN operator to match a list of values. Rather than writing a list of OR clauses we can use the IN as a shortcut. For example, say we have a list of cities and addresses. We can check if an address is located in our list using the IN operation. In this article, we will learn how to use th eIN operator.

The Syntax

The basic syntax of IN is as follows:

[value] IN (val1, val2, val3, …)

Value is the column we want to compare and the list to the right is the list of values we will accept.

Getting Setup

We will be using docker in this article, but feel free to install your database locally instead. Once you have docker installed, create a new file called docker-compose.yml and add the following.

version: '3'
 
services:
  db:
    image: mysql:latest
    container_name: db
    environment:
      MYSQL_ROOT_PASSWORD: root_pass
      MYSQL_DATABASE: app_db
      MYSQL_USER: db_user
      MYSQL_PASSWORD: db_user_pass
    ports:
      - "6033:3306"
    volumes:
      - dbdata:/var/lib/mysql
  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    container_name: pma
    links:
      - db
    environment:
      PMA_HOST: db
      PMA_PORT: 3306
      PMA_ARBITRARY: 1
    restart: always
    ports:
      - 8081:80

volumes:
  dbdata:

Next, run docker-compose up.

Now, navigate to http://localhost:8081/ to access phpMyAdmin. Then log in with the username root and pass root_pass.

Click the SQL tab and you are ready to go.

Creating a DB

In this article, we will need some data to work with. If you don't understand these commands, don't worry, we will cover them in later articles.

We will be using the sample db provided here: https://dev.mysql.com/doc/sakila/en/. However, we will only enter what we need rather than import the whole db.

With the SQL tab open (or your own sql cli going), let's first create our DB and select it.

create DATABASE if not EXISTS sakila;

USE sakila;

Next, let's create an actor table.

CREATE TABLE actor (
  actor_id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
  first_name VARCHAR(45) NOT NULL,
  last_name VARCHAR(45) NOT NULL,
  last_update TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY  (actor_id),
  KEY idx_actor_last_name (last_name)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

And finally, let's enter a few rows.

INSERT INTO actor VALUES 
(1,'PENELOPE','GUINESS','2006-02-15 04:34:33'),
(2,'NICK','WAHLBERG','2006-02-15 04:34:33'),
(3,'ED','CHASE','2006-02-15 04:34:33'),
(4,'JENNIFER','DAVIS','2006-02-15 04:34:33'),
(5,'JOHNNY','LOLLOBRIGIDA','2006-02-15 04:34:33'),
(6,'BETTE','NICHOLSON','2006-02-15 04:34:33'),
(7,'GRACE','MOSTEL','2006-02-15 04:34:33'),
(8,'MATTHEW','JOHANSSON','2006-02-15 04:34:33'),
(9,'GRACE','JOHANSSON','2006-02-15 04:34:33')

An Example

Let’s say want to select actors with either last name GUINESS or CHASE. We could use multiple OR clauses.

SELECT * FROM actor WHERE last_name = 'GUINESS' OR last_name = 'CHASE';

If we needed to add more countries, the OR clauses can get long. Instead, we can replace that with the IN operator.

SELECT * FROM actor WHERE last_name IN ('GUINESS', 'CHASE');