PostgreSQL Tutorial: Connect To a PostgreSQL Database Server

Summary: in this tutorial, you will learn how to connect to the PostgreSQL Database Server via an interactive terminal program called psql and via the pgAdmin application.

When you installed the PostgreSQL database server, the PostgreSQL installer also installed some useful tools for working with the PostgreSQL database server. In this tutorial, you will learn how to connect to the PostgreSQL database server via the following tools:

• psql – a terminal-based front-end to PostgreSQL database server.
• pgAdmin – a web-based front-end to PostgreSQL database server.

1) Connect to PostgreSQL database server using psql

psql is an interactive terminal program provided by PostgreSQL. It allows you to interact with the PostgreSQL database server such as executing SQL statements and managing database objects.

The following steps show you how to connect to the PostgreSQL database server via the psql program:

First, launch the psql program and connect to the PostgreSQL Database Server using the postgres user:

Second, enter all the information such as Server, Database, Port, Username, and Password. If you press Enter, the program will use the default value specified in the square bracket [] and move the cursor to the new line. For example, localhost is the default database server. In the step for entering the password for user postgres, you need to enter the password the user postgres that you chose during the PostgreSQL installation.

Third, interact with the PostgreSQL Database Server by issuing an SQL statement. The following statement returns the current version of PostgreSQL:

SELECT version();

Please do not forget to end the statement with a semicolon (;). After pressing Enter, psql will return the current PostgreSQL version on your system.

2) Connect to PostgreSQL database server using pgAdmin

The second way to connect to a database is by using a pgAdmin application. The pgAdmin application allows you to interact with the PostgreSQL database server via an intuitive user interface.

The following illustrates how to connect to a database using pgAdmin GUI application:

First, launch the pgAdmin application.

The pgAdmin application will launch on the web browser as shown in the following picture:

Second, right-click the Servers node and select Create > Server… menu to create a server

Third, enter the server name e.g., PostgreSQL and click the Connection tab:

Fourth, enter the host and password for the postgres user and click the Save button:

Fifth, click on the Servers node to expand the server. By default, PostgreSQL has a database named postgres as shown below:

Sixth, open the query tool by choosing the menu item Tool > Query Tool or click the lightning icon.

Seventh, enter the query in the Query Editor, click the Execute button, you will see the result of the query displaying in the Data Output tab:

Connect to PostgreSQL database from other applications

Any application that supports ODBC or JDBC can connect to the PostgreSQL database server. In addition, if you develop an application that uses a specific driver, the application can connect to the PostgreSQL database server as well:

• Connect to PostgreSQL from Python
• Connect to PostgreSQL from Java

In this tutorial, you’ve learned how to connect to the PostgreSQL database server by using different client tools including psql and pgAdmin GUI application.