Working with Replace (String Function) in MySQL

Intro

MySQL provides the REPLACE string function which allows you to replace substrings in a string column. There is a REPLACE statement which works differently, so it is worth noting this is the REPLACE string function. In this article, we will learn how to use REPLACE in MySQL.

The Syntax

The basic syntax of a REPLACE is as follows:

UPDATE
  SET REPLACE(column_name, old_string, new_string)
  WHERE [conditions];

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      VARCHAR(16)     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');

An Example

Now that we are set up, let's update all 'M' strings in the gender with 'Male'.

UPDATE employees 
SET 
    gender = REPLACE(
      gender,
      'M',
      'Male'
    );

Now, let's see our results.

select  * from employees;

emp_no	birth_date	first_name	last_name	gender	hire_date
10001	1953-09-02	Georgi	Facello	Male	1986-06-26
10002	1964-06-02	Bezalel	Simmel	F	1985-11-21
10003	1959-12-03	Parto	Bamford	Male	1986-08-28
10004	1954-05-01	Chirstian	Koblick	Male	1986-12-01
10005	1955-01-21	Kyoichi	Maliniak	Male	1989-09-12

Working with Replace (String Function) in MySQL

05.25.2022

Intro

The Syntax

Getting Setup

Creating a DB

An Example

How to use PATINDEX in Sql Server

Working with Right in MySQL