Postgresql split_part function allows us to split a string in to a number of substrings. This function help when formatting columns for a specific query. In this article, we will learn how to use Split Part in Postgresql.
The basic syntax of a Split Part is as follows:
SELECT split_part(string, delimiter, position) FROM [table];
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:
Now, navigate to
http://localhost:8081/ to access phpMyAdmin. Then log in with the username
root and pass
Click the SQL tab and you are ready to go.
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.
Next, let's create an
film table. This is a slightly simplified version of the sakila database.
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(1), 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');
Let's try an example by splitting the birth date of the employees. To start, let's see how the split part function work.
select split_part(birth_date::TEXT, '-', 1) as year from employees
Here we force birth date to be a text type, we split on a hyphen, and we return the first result. We get the following.
Now, let's do a slightly more complex example where we split each of the date parts into year, month, and day.
select split_part(birth_date::TEXT, '-', 1) as year, split_part(birth_date::TEXT, '-', 2) as month, split_part(birth_date::TEXT, '-', 3) as date from employees;
The only change between each column is the last parameter, the index of that split part. We have 1, 2, 3 which correspond to the date string split by the hyphen. You can think of the result from
split_part as [1953, 09, 02].
The result is as follows.