PHP mysqli_result::free() Method: Usage and Examples

Releases the memory used by a result set.

The examples focus on the operation itself, including the important distinction: mysqli_close closes a connection, not just one result buffer.

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_result::free(...) — 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. Result methods operate on a mysqli_result produced by an actual SELECT.

<?php
$mysqli = new mysqli(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
$mysqli->set_charset('utf8mb4');
$result = $mysqli->query('SELECT id, email FROM users ORDER BY id LIMIT 3');
$result->free();
echo "Result buffer released";

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. Result methods operate on a mysqli_result produced by an actual SELECT. The SELECT filters a different subset of rows.

<?php
$mysqli = new mysqli(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
$mysqli->set_charset('utf8mb4');
$result = $mysqli->query('SELECT id, email FROM users WHERE active = 1 ORDER BY id LIMIT 2');
$result->free();
echo "Buffered SELECT finished and released";

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. Result methods operate on a mysqli_result produced by an actual SELECT. The SELECT filters a different subset of rows.

<?php
$mysqli = new mysqli(getenv('DB_HOST') ?: '127.0.0.1', getenv('DB_USER') ?: 'app', getenv('DB_PASSWORD') ?: '', getenv('DB_NAME') ?: 'demo');
$mysqli->set_charset('utf8mb4');
$result = $mysqli->query('SELECT id, email FROM users WHERE id > 10 ORDER BY id LIMIT 5');
$result->free();
echo "Buffered SELECT finished and released";

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

Do not fetch from a result after freeing it; close the statement or connection separately as needed.

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

• Releases the memory used by a result set.
• Do not fetch from a result after freeing it; close the statement or connection separately as needed.
• mysqli_close closes a connection, not just one result buffer.

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