Working with LOWER in Postgres

Intro

PostgreSQL provides the lower function to transform a string into all lower case letters. In this article, we will learn how to use LOWER in PostgreSQL.

The Syntax

The basic syntax of a LOWER is as follows:

SELECT LOWER(string);

• string: The string or varchar you want to lower case.

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: '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:

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.

Basic Example

The simple example is to lower case a string literal. Here is an example.

select lower('Hello World!') as lower_string;

Lower on a Table Column

We can also run lower on a column. Below we create an employee table.

CREATE TABLE employees (
    first_name VARCHAR (50) NOT NULL,
    last_name VARCHAR (50) NOT NULL
);

insert into employees (first_name, last_name) 
	values 
	('Keith', 'Holliday'),
	('Jon', 'Doe'),
	('Jane', 'Doe');

We can now run the lower function on the columns.

select 
  lower(first_name) as FirstName,
	lower(last_name) as LastName
from employees e;