How to Connect PHP to a PostgreSQL Database (Guide)

If you searched for how to connect PHP to a PostgreSQL database, here is the short answer: you use PHP's built-in PDO (PHP Data Objects) extension to open a connection with a database name, username, and password, then use that connection object to run SQL queries. This guide walks through every step with small, copy-pasteable code examples, so you can follow along even if you have never connected PHP to a database before.

PostgreSQL (often called "Postgres") is a free, open-source database. PHP is a popular language for building websites. Together, they let you build a site that saves and reads data, like a list of users, blog posts, or orders.

What you need before you start

• PHP installed on your computer, version 7.4 or newer (check with php -v in your terminal).
• PostgreSQL installed and running, with a database already created.
• The PDO PostgreSQL driver enabled. Most PHP installations include it, but if pdo_pgsql is missing, you may need to install a package like php-pgsql.
• Basic comfort with the command line and a text editor. You do not need to be a PHP or SQL expert.

Not sure how to create your first PostgreSQL table? Start with our beginner guide on creating tables, then come back here to connect PHP to it.

Step 1: Know your connection details

To connect to any PostgreSQL database, you need four pieces of information. Write these down before you start coding.

Step 2: Connect to PostgreSQL using PHP PDO

PDO is the recommended way to talk to a database from PHP. It works the same way for PostgreSQL, MySQL, and other databases, so the skills you learn here carry over. Create a new file called db.php and add this code:

<?php

$host = "localhost";
$port = "5432";
$dbname = "my_app";
$user = "postgres";
$password = "your_password";

$dsn = "pgsql:host=$host;port=$port;dbname=$dbname";

try {
    $pdo = new PDO($dsn, $user, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected to PostgreSQL successfully!";
} catch (PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}

Here is what each part does. $dsn stands for "Data Source Name" — it is a single string that tells PDO which database driver to use (pgsql) and where to find the database. new PDO($dsn, $user, $password) opens the actual connection and stores it in the $pdo variable. setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION) tells PDO to throw an error you can catch, instead of failing silently. The try/catch block runs your connection code, and if anything goes wrong, it prints a clear error message instead of crashing with a confusing PHP warning.

Run it

php db.php

If you see "Connected to PostgreSQL successfully!", your PHP script can talk to your database. If you see "Connection failed", double-check your host, port, database name, username, and password.

Step 3: Insert data into your PostgreSQL table

Once you are connected, you can save data. Imagine you have a table called users with columns id, name, and email. Here is how to insert a new row safely:

<?php
require "db.php";

$name = "Ada Lovelace";
$email = "ada@example.com";

$sql = "INSERT INTO users (name, email) VALUES (:name, :email)";
$stmt = $pdo->prepare($sql);
$stmt->execute([
    "name" => $name,
    "email" => $email
]);

echo "New user added!";

require "db.php" reuses the connection code from Step 2, so $pdo is already available. Notice the query uses :name and :email instead of the raw variables — these are called placeholders. $pdo->prepare() builds the query without filling in the values yet, and $stmt->execute() safely fills them in afterward. This pattern is called a prepared statement, and it protects your app from SQL injection, a common attack where malicious text is typed into a form to trick your database into running unwanted commands. Always use placeholders instead of pasting user input directly into a SQL string.

Step 4: Fetch and display data from PostgreSQL

Now let's read the data back out and print it. This is the same pattern you would use to list users on a webpage.

<?php
require "db.php";

$sql = "SELECT id, name, email FROM users ORDER BY id";
$stmt = $pdo->query($sql);

while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    echo $row["id"] . ": " . $row["name"] . " (" . $row["email"] . ")\n";
}

$pdo->query() runs a SELECT statement that has no user input, so it is safe to run directly (use prepare() instead whenever a query includes a variable). $stmt->fetch(PDO::FETCH_ASSOC) pulls back one row at a time as an associative array, meaning you can access columns by name, like $row["name"]. The while loop keeps calling fetch() until there are no more rows, printing each user as it goes.

PDO vs. the native pg_connect functions

You may also see PHP code that uses pg_connect() and pg_query() instead of PDO. Both can connect PHP to PostgreSQL, but they are not the same.

For beginners, stick with PDO. It is the more widely used approach, and if you ever switch databases later, most of your code stays the same.

Common connection errors and how to fix them

• "could not find driver" — the pdo_pgsql extension is not enabled. Enable it in your php.ini file and restart PHP.
• "connection refused" — PostgreSQL is not running, or the host/port is wrong. Confirm PostgreSQL is started and listening on port 5432.
• "password authentication failed" — the username or password is incorrect, or PostgreSQL's pg_hba.conf file is not allowing that login method.
• "database does not exist" — check the spelling of your database name, or create the database first.

You now know how to connect PHP to PostgreSQL, insert data safely, and fetch it back out. From here, try building a simple form that saves data using the insert code above, then a page that lists it using the fetch code. That small project covers most of what a real web app needs to talk to its database.