PHP pg_query() Function: Usage and Examples

Executes a SQL string synchronously against the connection.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Executes a SQL string synchronously against the connection.

Syntax and Return Value

pg_query(...)

The return value and exceptional cases depend on the call described here: Use pg_query_params rather than concatenating user input into SQL values.

Requirements: install and enable the corresponding PHP driver or extension and configure the service before running the examples.

Example 1: Basic Use

Requires a reachable PostgreSQL server and the pgsql PHP extension; asynchronous requests must be drained with pg_get_result.

<?php
$host = getenv('DB_HOST'); $user = getenv('DB_USER'); $password = getenv('DB_PASSWORD'); $database = getenv('DB_NAME');
if (!$host || !$user || $password === false || !$database) throw new RuntimeException('Missing PostgreSQL configuration');
$pg = pg_connect('host=' . $host . ' dbname=' . $database . ' user=' . $user . ' password=' . $password);
if (!$pg) { throw new RuntimeException('PostgreSQL connection failed'); }
$result = pg_query($pg,"SELECT 2 AS item_id");
echo pg_fetch_result($result,0,"item_id");

Example 2: A Second Scenario

Requires a reachable PostgreSQL server and the pgsql PHP extension; asynchronous requests must be drained with pg_get_result.

<?php
$host = getenv('DB_HOST'); $user = getenv('DB_USER'); $password = getenv('DB_PASSWORD'); $database = getenv('DB_NAME');
if (!$host || !$user || $password === false || !$database) throw new RuntimeException('Missing PostgreSQL configuration');
$pg = pg_connect('host=' . $host . ' dbname=' . $database . ' user=' . $user . ' password=' . $password);
if (!$pg) { throw new RuntimeException('PostgreSQL connection failed'); }
$result = pg_query($pg,"SELECT 4 AS item_id");
echo pg_fetch_result($result,0,"item_id");

Example 3: Practical Checks

Requires a reachable PostgreSQL server and the pgsql PHP extension; asynchronous requests must be drained with pg_get_result.

<?php
$host = getenv('DB_HOST'); $user = getenv('DB_USER'); $password = getenv('DB_PASSWORD'); $database = getenv('DB_NAME');
if (!$host || !$user || $password === false || !$database) throw new RuntimeException('Missing PostgreSQL configuration');
$pg = pg_connect('host=' . $host . ' dbname=' . $database . ' user=' . $user . ' password=' . $password);
if (!$pg) { throw new RuntimeException('PostgreSQL connection failed'); }
$result = pg_query($pg,"SELECT 6 AS item_id");
echo pg_fetch_result($result,0,"item_id");

Important Behavior and Edge Cases

Use pg_query_params rather than concatenating user input into SQL values.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Executes a SQL string synchronously against the connection.
• Use pg_query_params rather than concatenating user input into SQL values.
• pg_send_query queues asynchronous execution instead of blocking for a result.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.