Working with Concat in MySQL

Intro

MySQL provides a few ways to concatenate strings. We can use the CONCAT and CONCAT_WS function. In this article, we will learn how to concatenate strings in MySQL.

The Syntax

The basic syntax of a CONCAT is as follows:

SELECT CONCAT(string1, string2, ...more_strings);

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. We will be using the sample db provided here: https://dev.mysql.com/doc/employee/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;

CREATE TABLE employees (
    emp_no      INT             NOT NULL,
    birth_date  DATE            NOT NULL,
    first_name  VARCHAR(14)     NOT NULL,
    last_name   VARCHAR(16)     NOT NULL,
    gender      ENUM ('M','F')  NOT NULL,    
    hire_date   DATE            NOT NULL,
    PRIMARY KEY (emp_no)
);

Now, let's enter a few rows

INSERT INTO employees VALUES (10001,'1953-09-02','Georgi','Facello','M','1986-06-26'),
(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21'),
(10003,'1959-12-03','Parto','Bamford','M','1986-08-28'),
(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01'),
(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12'),
(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02'),
(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10'),
(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15'),
(10009,'1952-04-19','Sumant','Peac','F','1985-02-18');

The CONCAT function

We can accomplish the same using the CONCAT function.

select 
	CONCAT(first_name, ' ', last_name) as full_name
from employees e ;

full_name
Bezalel Simmel
Parto Bamford
Chirstian Koblick
Kyoichi Maliniak
George Facello

The CONCAT_WS function

We can accomplish the same using the CONCAT_WS function, but this function also provides more. We can specify a separator then a list of strings. The prevents us from having to type our separate multiple times.

To get a sense of this, let's also add in the birth date to concatenate. We will use a space as the separator. Notice, in the previous example, we would have needed to type space multiple times.

select 
	CONCAT_WS(' ', first_name, last_name, birth_date) as full_name_and_date
from employees e;

full_name_and_date
Bezalel Simmel 1964-06-02
Parto Bamford 1959-12-03
Chirstian Koblick 1954-05-01
Kyoichi Maliniak 1955-01-21
George Facello 1953-09-02