PHP mysqli_query() Function: Usage and Examples

Executes SQL using the procedural API.

The examples focus on the operation itself, including the important distinction: mysqli_fetch_assoc reads result rows after a query.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Syntax and Return Value

mysqli_query(...) — requires the corresponding optional extension

The displayed signature describes the API or identifies any correction or optional dependency. When a parameter is optional, supply it only when the task requires it.

Example 1: Basic Use

Examples assume a demo database containing users(id, email, active), products(id, name, price), and orders(id, user_id, total) as required by the query.

<?php
$link = mysqli_connect(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
mysqli_set_charset($link, 'utf8mb4');
$result = mysqli_query($link, 'SELECT id, email FROM users ORDER BY id LIMIT 3');
while ($row = mysqli_fetch_assoc($result)) { echo $row["email"] . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 2: Checking Behavior

Examples assume a demo database containing users(id, email, active), products(id, name, price), and orders(id, user_id, total) as required by the query. The SELECT filters a different subset of rows.

<?php
$link = mysqli_connect(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
mysqli_set_charset($link, 'utf8mb4');
$result = mysqli_query($link, 'SELECT id, email FROM users WHERE active = 1 ORDER BY id LIMIT 2');
while ($row = mysqli_fetch_assoc($result)) { echo $row["email"] . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 3: Practical Example

Examples assume a demo database containing users(id, email, active), products(id, name, price), and orders(id, user_id, total) as required by the query. The SELECT filters a different subset of rows.

<?php
$link = mysqli_connect(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
mysqli_set_charset($link, 'utf8mb4');
$result = mysqli_query($link, 'SELECT id, email FROM users WHERE id > 10 ORDER BY id LIMIT 5');
while ($row = mysqli_fetch_assoc($result)) { echo $row["email"] . PHP_EOL; }

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Important Behavior and Edge Cases

Use mysqli_prepare and bound values for any untrusted data.

This API is supplied by an optional extension that is not installed in the local test runtime, or requires a different PHP version. The example must be verified in a matching environment.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Executes SQL using the procedural API.
• Use mysqli_prepare and bound values for any untrusted data.
• mysqli_fetch_assoc reads result rows after a query.

Use mysqli_query when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.