Working with Between in Postgres

Intro

The BETWEEN operator allows you to filter for values in between two other values. For example, we could select items that are in a specific date range or houses in between a price range. In this article, we will learn how to use BETWEEN in Postgres.

The Syntax

The basic syntax of BETWEEN is as follows:

[value] BETWEEN [low] AND [high]

Value is the item we want to compare, and high and low represent our range.

Getting Setup

For our setup, we will use docker compose to create a Postgres database and to connect phpmyadmin. Start by copying the following into a docker compose file called docker-compose.yml

version: '3'
 
services:
  db:
    image: 'postgres:latest'
    ports:
      - 5432:5432
    environment:
      POSTGRES_USER: username
      POSTGRES_PASSWORD: password
      POSTGRES_DB: default_database
    volumes:
      - psqldata:/var/lib/postgresql

  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    links:
      - db
    environment:
      PMA_HOST: db
      PMA_PORT: 3306
      PMA_ARBITRARY: 1
    restart: always
    ports:
      - 8081:80

volumes:
  psqldata:

We can run this file, we can use docker-compose up. One this is done, open up phpmyadmin by going to http://localhost:8081.

You can then login by leaving the host empty and using the following credentials.

POSTGRES_USER: username
POSTGRES_PASSWORD: password

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.Postgres.com/doc/sakila/en/. However, we will only enter what we need rather than import the whole db.

Next, let's create an actor table.

CREATE TABLE actor (
  actor_id smallint,
  first_name VARCHAR(45) NOT NULL,
  last_name VARCHAR(45) NOT NULL,
  last_update TIMESTAMP(0) NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY  (actor_id)
) ;

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')

An Example

Let’s use the following example to select actors in between a specific id range.

SELECT * FROM actor WHERE actor_id BETWEEN 3 AND 6;

We can also use the NOT keyword to filter values outside of the range.

SELECT * FROM actor WHERE actor_id NOT BETWEEN 3 AND 6;

We can also use between two dates. For this, we must use the CAST function to ensure our values are used as dates. For example, we want to compare 2003-01-01, we must use the following to tell Postgres it is a date CAST('2003-01-01' AS DATE).

SELECT * 
	FROM actor 
WHERE last_update 
	BETWEEN CAST('2006-02-14' AS DATE) AND CAST('2006-02-16' AS DATE);