Introduction

PostgreSQL is an open-source relational database management system. It is known for its reliability, scalability, and extensibility, making it a popular choice for enterprise-level applications. In this tutorial, we will cover how to install and set up PostgreSQL in Linux, how to create a database and table, how to insert values into the table, how to log in to a user and database, and how to completely remove PostgreSQL including all related files.

Prerequisites

Before we begin, make sure you have the following prerequisites:

• Linux installed on your system
• A terminal emulator with root privileges

Step 1: Installing PostgreSQL

To install PostgreSQL in Linux, follow these steps:

Note that while the instructions for creating a database, inserting values, and logging in to a user and database are applicable to PostgreSQL on any Linux distribution, the installation and deletion commands used in this tutorial are specific to Arch Linux.

1. Open the terminal emulator.

2. Update the package list:

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sudo pacman -Syu

1. Install PostgreSQL using the following command:

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sudo pacman -S postgresql

This will install PostgreSQL on your system.

Step 2: Setting up PostgreSQL

After installing PostgreSQL, you need to perform some initial setup before you can use it. Follow these steps:

1. Initialize the PostgreSQL data directory using the following command:

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sudo -iu postgres initdb -D /var/lib/postgres/data

This command initializes the PostgreSQL data directory with default settings.

1. Start the PostgreSQL service:

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sudo systemctl start postgresql.service

1. Enable the PostgreSQL service:

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sudo systemctl enable postgresql.service

This command ensures that PostgreSQL starts automatically on system boot.

Step 3: Creating a Database and Table

After setting up PostgreSQL, you can create a database and table. Follow these steps:

1. Log in to the PostgreSQL server as the postgres user:

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sudo -iu postgres psql

1. Create a new database using the following command:

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CREATE DATABASE mydb;

This command creates a new database named mydb.

1. Connect to the newly created database using the following command:

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\c mydb

1. Create a new table in the database using the following command:

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CREATE TABLE mytable (id serial PRIMARY KEY, name VARCHAR(50), age INTEGER);

This command creates a new table named mytable with three columns: id, name, and age.

Step 4: Inserting Values into the Table

After creating the database and table, you can insert values into the table. Follow these steps:

1. Insert a new row into the table using the following command:

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INSERT INTO mytable (name, age) VALUES ('John Doe', 30);

This command inserts a new row into the mytable table with name set to John Doe and age set to 30.

1. View the contents of the table using the following command:

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SELECT * FROM mytable;

This command displays the contents of the mytable table.

Step 5: Logging in to a User and Database

After creating a database and table, you may want to log in to a specific user and database. Follow these steps:

1. Log in to the PostgreSQL server as the postgres user:

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sudo -iu postgres psql

1. Create a new user using the following command:

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CREATE USER myuser WITH PASSWORD 'mypassword';

This command creates a new user named myuser with the password mypassword.

1. Grant permissions to the new user using the following command:

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GRANT ALL PRIVILEGES ON DATABASE mydb TO myuser;

This command grants all privileges to the mydb database to the myuser user.

1. Exit the PostgreSQL prompt using the following command:

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\q

1. Log in to the PostgreSQL server as the myuser user:

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psql -U myuser -d mydb

This command logs in to the mydb database as the myuser user.

Step 6: Removing PostgreSQL

If you want to remove PostgreSQL from your Linux system, you can do so using the following steps:

1. Stop the PostgreSQL service:

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sudo systemctl stop postgresql.service

1. Remove the PostgreSQL package using the following command:

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sudo pacman -Rs postgresql

1. Remove the PostgreSQL data directory and configuration files using the following command:

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sudo rm -r /var/lib/postgres/data
sudo rm -rf /etc/postgresql/

These commands will remove the PostgreSQL data directory (/var/lib/postgres/) and configuration files (/etc/postgresql/).

Conclusion

PostgreSQL is a powerful and reliable relational database management system that is widely used in enterprise-level applications. In this tutorial, we covered how to install and set up PostgreSQL in Linux, how to create a database and table, how to insert values into the table, how to log in to a user and database, and how to completely remove PostgreSQL including all related files.

References:

PostgreSQL-ArchLinux
postgresql.org