# How to Connect # Connecting with Node.js This guide explains how to establish a connection between a Node.js application and a PostgreSQL database using the `pg` package. It walks through the necessary setup, configuration, and execution of a simple SQL query. ## **Variables** Certain parameters must be provided to establish a successful connection to a PostgreSQL database. Below is a breakdown of each required variable, its purpose, and where to find it. Here’s what each variable represents:
**Variable** **Description** **Purpose**
`USER`PostgreSQL username, from the Elestio service overview pageIdentifies the database user who has permission to access the PostgreSQL database.
`PASSWORD`PostgreSQL password, from the Elestio service overview pageThe authentication key required for the specified `USER` to access the database
`HOST`Hostname for PostgreSQL connection, from the Elestio service overview pageThe address of the server hosting the PostgreSQL database.
`PORT`Port for PostgreSQL connection, from the Elestio service overview pageThe network port is used to connect to PostgreSQL. The default port is `5432`.
`DATABASE`Database Name for PostgreSQL connection, from the Elestio service overview pageThe name of the database being accessed. A PostgreSQL instance can contain multiple databases.
These values can usually be found in the Elestio service overview details as shown in the image below, make sure to take a copy of these details and add it to the code moving ahead. [![Screenshot 2025-03-20 at 12.34.30 PM.jpg](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/screenshot-2025-03-20-at-12-34-30-pm.jpg)](https://docs.elest.io/uploads/images/gallery/2025-03/screenshot-2025-03-20-at-12-34-30-pm.jpg) ## **Prerequisites** - **Install Node.js and NPM** - Check if Node.js is installed by running:
`node -v`
- If not installed, download it from [nodejs.org](https://nodejs.org/) and install. - Verify npm installation:
`npm -v`
- **Install the `pg` Package** The `pg` package enables Node.js applications to interact with PostgreSQL. Install it using:
`npm install pg --save`
## **Code** Once all prerequisites are set up, create a new file named `pg.js` and add the following code: ```javascript const pg = require("pg"); // Database connection configuration const config = { user: "USER", password: "PASSWORD", host: "HOST", port: "PORT", database: "DATABASE", }; // Create a new PostgreSQL client const client = new pg.Client(config); // Connect to the database client.connect((err) => { if (err) { console.error("Connection failed:", err); return; } console.log("Connected to PostgreSQL"); // Run a test query to check the PostgreSQL version client.query("SELECT VERSION()", [], (err, result) => { if (err) { console.error("Query execution failed:", err); client.end(); return; } console.log("PostgreSQL Version:", result.rows[0]); // Close the database connection client.end((err) => { if (err) console.error("Error closing connection:", err); }); }); }); ``` To execute the script, open the terminal or command prompt and navigate to the directory where `pg.js`. Once in the correct directory, run the script with the command ```bash node pg.js ``` If the connection is successful, the terminal will display output similar to: ```bash Connected to PostgreSQL PostgreSQL Version: { version: 'PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit' } ``` # Connecting with Python This guide explains how to establish a connection between a **Python** application and a **PostgreSQL** database using the **`psycopg2-binary`** package. It walks through the necessary setup, configuration, and execution of a simple SQL query. ### **Variables** To connect to a PostgreSQL database, you only need one environment variable — the **connection URI**. This URI contains all the necessary information like username, password, host, port, and database name.
VariableDescriptionPurpose
**POSTGRESQL\_URI**Full PostgreSQL connection string (from the Elestio service overview page)Provides all necessary credentials and endpoint details in a single URI format.
The URI will look like this: ```bash postgresql://:@:/ ``` You can find the details needed in the URI from the **Elestio service overview** details. Copy and replace the variables carefully in the URI example provided above. ![image.png](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/ZvEimage.png) ### **Prerequisites** ##### **Install Python** Check if Python is installed by running: ```bash python --version ``` If not installed, download it from [python.org](https://www.python.org/) and install it. ##### **Install `psycopg2-binary` Package** The `psycopg2-binary` package enables Python applications to interact with PostgreSQL. Install it using: ```bash pip install psycopg2-binary ``` ### **Code** Once all prerequisites are set up, create a new file named `pg.py` and add the following code and replace the `POSTGRESQL_URI` with actual link or in environment setup as you wish: ```python import psycopg2 def get_db_version(): try: db_connection = psycopg2.connect('POSTGRESQL_URI') db_cursor = db_connection.cursor() db_cursor.execute('SELECT VERSION()') db_version = db_cursor.fetchone()[0] return db_version except Exception as e: print(f"Database connection error: {e}") return None finally: if 'db_cursor' in locals(): db_cursor.close() if 'db_connection' in locals(): db_connection.close() def display_version(): version = get_db_version() if version: print(f"Connected to PostgreSQL: {version}") if __name__ == "__main__": display_version() ``` To execute the script, open the terminal or command prompt and navigate to the directory where `pg.py`. Once in the correct directory, run the script with the command ```bash python pg.py ``` If the connection is successful, the terminal will display output similar to: ``` Connected to PostgreSQL: PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit ```
# Connecting with PHP This guide explains how to establish a connection between a **PHP** application and a **PostgreSQL** database using the built-in `PDO` extension. It walks through the necessary setup, configuration, and execution of a simple SQL query. ### **Variables** To connect to a PostgreSQL database, you only need one environment variable — the **connection URI**. This URI contains all the necessary information like username, password, host, port, and database name.
VariableDescriptionPurpose
**POSTGRESQL\_URI**Full PostgreSQL connection string (from the Elestio service overview page)Provides all necessary credentials and endpoint details in a single URI format.
The URI will look like this: ```bash postgresql://:@:/ ``` You can find the details needed in the URI from the **Elestio service overview** details. Copy and replace the variables carefully in the URI example provided above. ![image.png](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/ZvEimage.png) ### **Prerequisites** ##### **Install PHP** Check if PHP is installed by running: ```bash php -v ``` If not installed, download and install it from [https://www.php.net/downloads.php](https://www.php.net/downloads.php). ### **Code** Once all prerequisites are set up, create a new file named `pg.php` and add the following code and replace the `POSTGRESQL_URI` with actual link or in environment setup as you wish: ```php query("SELECT VERSION()")->fetchColumn(); echo $version; ``` To execute the script, open the terminal or command prompt and navigate to the directory where `pg.php`. Once in the correct directory, run the script with the command ```kotlin php pg.php ``` If the connection is successful, the terminal will display output similar to: ```bash PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit ``` # Connecting with Go This guide explains how to establish a connection between a **Go (Golang)** application and a **PostgreSQL** database using the `github.com/lib/pq` driver. It walks through the necessary setup, configuration, and execution of a simple SQL query. ### **Variables** To connect to a PostgreSQL database, you only need one environment variable — the **connection URI**. This URI contains all the necessary information like username, password, host, port, and database name.
VariableDescriptionPurpose
**POSTGRESQL\_URI**Full PostgreSQL connection string (from the Elestio service overview page)Provides all necessary credentials and endpoint details in a single URI format.
The URI will look like this: ```bash postgresql://:@:/ ``` You can find the details needed in the URI from the **Elestio service overview** details. Copy and replace the variables carefully in the URI example provided above. ![image.png](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/ZvEimage.png) ### **Prerequisites** ##### **Install Go** Check if Go is installed by running: ```bash go version ``` If not installed, download and install it from [https://go.dev/dl/](https://go.dev/dl/). ##### **Install `pq` Package** Install the `pq` driver using: ```bash go get github.com/lib/pq ``` ### **Code** Once all prerequisites are set up, create a new file named `main.go` and add the following code, and replace the `POSTGRESQL_URI` with actual link or in environment setup as you wish: ```go package main import ( "database/sql" "fmt" "log" "net/url" _ "github.com/lib/pq" ) func getDBConnection(connectionString string) (*sql.DB, error) { parsedURL, err := url.Parse(connectionString) if err != nil { return nil, fmt.Errorf("Failed to parse connection string: %v", err) } db, err := sql.Open("postgres", parsedURL.String()) if err != nil { return nil, fmt.Errorf("Failed to open database connection: %v", err) } return db, nil } func main() { connectionString := "POSTGRESQL_URI" db, err := getDBConnection(connectionString) if err != nil { log.Fatal(err) } defer db.Close() query := "SELECT current_database(), current_user, version()" rows, err := db.Query(query) if err != nil { log.Fatal("Failed to execute query:", err) } defer rows.Close() for rows.Next() { var dbName, user, version string if err := rows.Scan(&dbName, &user, &version); err != nil { log.Fatal("Failed to scan row:", err) } fmt.Printf("Database: %s\nUser: %s\nVersion: %s\n", dbName, user, version) } } ``` To execute the script, open the terminal or command prompt and navigate to the directory where `main.go`. Once in the correct directory, run the script with the command ```bash go run main.go ``` If the connection is successful, the terminal will display output similar to: ``` Database: Elestio User: postgres Version: PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit ```
# Connecting with Java This guide explains how to establish a connection between a **Java** application and a **PostgreSQL** database using the **JDBC driver**. It walks through the necessary setup, configuration, and execution of a simple SQL query. ## **Variables** Certain parameters must be provided to establish a successful connection to a PostgreSQL database. Below is a breakdown of each required variable, its purpose, and where to find it. Here’s what each variable represents:
**Variable** **Description** **Purpose**
`USER`PostgreSQL username, from the Elestio service overview pageIdentifies the database user who has permission to access the PostgreSQL database.
`PASSWORD`PostgreSQL password, from the Elestio service overview pageThe authentication key required for the specified `USER` to access the database
`HOST`Hostname for PostgreSQL connection, from the Elestio service overview pageThe address of the server hosting the PostgreSQL database.
`PORT`Port for PostgreSQL connection, from the Elestio service overview pageThe network port is used to connect to PostgreSQL. The default port is `5432`.
`DATABASE`Database Name for PostgreSQL connection, from the Elestio service overview pageThe name of the database being accessed. A PostgreSQL instance can contain multiple databases.
These values can usually be found in the Elestio service overview details, as shown in the image below. Make sure to take a copy of these details and add them to the code moving ahead. ![Screenshot 2025-03-20 at 12.34.30 PM.jpg](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/screenshot-2025-03-20-at-12-34-30-pm.jpg) ### **Prerequisites** ##### **Install Java & JDBC driver** Check if Java is installed by running: ```bash java -version ``` If not installed, install it first and then download and install **JDBC** driver from [https://jdbc.postgresql.org/download/](https://jdbc.postgresql.org/download/) or if you have Maven installed, run the following command with updated version of the driver: ```bash mvn org.apache.maven.plugins:maven-dependency-plugin:2.8:get -Dartifact=org.postgresql:postgresql:42.7.5:jar -Ddest=postgresql-42.7.5.jar ``` ## **Code** Once all prerequisites are set up, create a new file named `Pg.java` and add the following code: ```java import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.HashMap; import java.util.Map; public class Pg { private static class ConnectionConfig { private final String host; private final String port; private final String database; private final String username; private final String password; public ConnectionConfig(String host, String port, String database, String username, String password) { this.host = host; this.port = port; this.database = database; this.username = username; this.password = password; } public String getConnectionUrl() { return String.format("jdbc:postgresql://%s:%s/%s?sslmode=require", host, port, database); } public boolean isValid() { return host != null && !host.isEmpty() && port != null && !port.isEmpty() && database != null && !database.isEmpty(); } } private static Map parseArguments(String[] args) { Map config = new HashMap<>(); for (int i = 0; i < args.length - 1; i++) { String key = args[i].toLowerCase(); String value = args[++i]; config.put(key, value); } return config; } private static ConnectionConfig createConfig(Map args) { return new ConnectionConfig( args.get("-host"), args.get("-port"), args.get("-database"), args.get("-username"), args.get("-password") ); } private static void validateConnection(Connection connection) throws SQLException { try (Statement stmt = connection.createStatement(); ResultSet rs = stmt.executeQuery("SELECT version()")) { if (rs.next()) { System.out.println("Database Version: " + rs.getString("version")); } } } public static void main(String[] args) { try { // Load PostgreSQL driver Class.forName("org.postgresql.Driver"); // Parse and validate configuration Map parsedArgs = parseArguments(args); ConnectionConfig config = createConfig(parsedArgs); if (!config.isValid()) { System.err.println("Error: Missing required connection parameters (host, port, database)"); return; } // Establish connection and validate try (Connection conn = DriverManager.getConnection( config.getConnectionUrl(), config.username, config.password)) { System.out.println("Successfully connected to the database!"); validateConnection(conn); } } catch (ClassNotFoundException e) { System.err.println("Error: PostgreSQL JDBC Driver not found"); e.printStackTrace(); } catch (SQLException e) { System.err.println("Database connection error:"); e.printStackTrace(); } } } ``` To execute the script, open the terminal or command prompt and navigate to the directory where `Pg.java`. Once in the correct directory, run the script with the command (Update the variables with actual values acquired from previous steps.) ```bash javac Pg.java && java -cp postgresql-42.7.5.jar:. Pg -host HOST -port PORT -database DATABASE -username avnadmin -password PASSWORD ``` If the connection is successful, the terminal will display output similar to: ```bash Successfully connected to the database! Database Version: PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit ``` # Connecting with psql This guide explains how to connect to a **PostgreSQL** database using the **`psql`** command-line tool. It walks through the necessary setup, connection process, and execution of a simple SQL query. ### **Variables** To connect to a PostgreSQL database, you only need one environment variable — the **connection URI**. This URI contains all the necessary information like username, password, host, port, and database name.
VariableDescriptionPurpose
**POSTGRESQL\_URI**Full PostgreSQL connection string (from the Elestio service overview page)Provides all necessary credentials and endpoint details in a single URI format.
The URI will look like this: ```bash postgresql://:@:/ ``` You can find the details needed in the URI from the **Elestio service overview** details. Copy and replace the variables carefully in the URI example provided above. ![image.png](https://docs.elest.io/uploads/images/gallery/2025-03/scaled-1680-/ZvEimage.png) ### **Prerequisites** While following this tutorial, you will need to have **`psql`** already installed; if not head over to [https://www.postgresql.org/download/](https://www.postgresql.org/download/) and download it first. ### **Connecting to PostgreSQL** Open your terminal and run the following command to connect to your PostgreSQL database using the full connection URI: ```bash psql POSTGRESQL_URI ```
If the connection is successful, you’ll see output similar to this. Here it will show you the database you tried to connect to, which in this case is Elestio: ``` psql (17.4, server 16.8 (Debian 16.8-1.pgdg120+1)) SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off, ALPN: none) Type "help" for help. Elestio=# ``` To ensure you're connected correctly, run this command inside the `psql` prompt: ```bash SELECT version(); ``` You should receive output like the following: ``` version --------------------------------------------------------------------------------------------------------------------- PostgreSQL 16.8 (Debian 16.8-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit (1 row) ```
# Connecting with pgAdmin **pgAdmin** is a widely used graphical interface for PostgreSQL that allows you to manage, connect to, and run queries on your databases with ease. ### **Variables** To connect using `pgAdmin`, you'll need the following connection parameters. When you deploy a PostgreSQL service on Elestio, you also get a pgAdmin dashboard configured for you to use with these variables. These details are available in the **Elestio service overview page**:
VariableDescriptionPurpose
**USER**pgAdmin usernameIdentifies the pgAdmin user with access permission.
**PASSWORD**pgAdmin passwordAuthentication key for the `USER`.
You can find these values in your Elestio project dashboard under **Admin** section. [![Screenshot 2025-04-01 at 3.49.57 PM.jpg](https://docs.elest.io/uploads/images/gallery/2025-04/scaled-1680-/screenshot-2025-04-01-at-3-49-57-pm.jpg)](https://docs.elest.io/uploads/images/gallery/2025-04/screenshot-2025-04-01-at-3-49-57-pm.jpg) ### **Prerequisites** Make sure the **PostgreSQL** service is correctly deployed on Elestio and you are able to access the Admin section like the one in the image above. ### **Setting Up the Connection** 1. Launch **pgAdmin** from the Admin UI URL and log in with the credentials acquired in the steps before. ![Screenshot 2025-04-01 at 3.51.28 PM.jpg](https://docs.elest.io/uploads/images/gallery/2025-04/scaled-1680-/screenshot-2025-04-01-at-3-51-28-pm.jpg) 2. Click on **"Create"** and select **"Server…"** from the dropdown, or find **Add New Server** from the quick links![Screenshot 2025-04-01 at 3.55.59 PM.jpg](https://docs.elest.io/uploads/images/gallery/2025-04/scaled-1680-/screenshot-2025-04-01-at-3-55-59-pm.jpg) 3. In the **General** tab: - Enter a name for your connection (e.g., `Trial pgAdmin Connection`).![image.png](https://docs.elest.io/uploads/images/gallery/2025-04/scaled-1680-/image.png) 4. Go to the **Connection** tab and enter the following details: - **Host name/address**: `HOSTNAME` - **Port**: `PORT` - **Maintenance database**: `DATABASE` - **Username**: `USERNAME` - **Password**: `PASSWORD` ![image.png](https://docs.elest.io/uploads/images/gallery/2025-04/scaled-1680-/6v6image.png)