PHP mysqli_stmt::close() Method: Usage and Examples

Closes the prepared statement and frees its associated server and client resources.

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

What It Does

Closes the prepared statement and frees its associated server and client resources.

Syntax and Return Value

mysqli_stmt::close(...)

The return value and exceptional cases depend on the call described here: Do not execute or fetch from the same statement after closing it.

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

Example 1: Basic Use

The SELECT assumes users(id,email) in an actual MySQL database; output depends on its rows.

<?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 database configuration');
$mysqli = new mysqli($host, $user, $password, $database);
$mysqli->set_charset('utf8mb4');
$userId = 3;
$stmt = $mysqli->prepare("SELECT id, email FROM users WHERE id >= ? ORDER BY id");
$stmt->bind_param("i", $userId);
$stmt->execute();
$stmt->close();
echo "Prepared statement closed";

Example 2: A Second Scenario

The SELECT assumes users(id,email) in an actual MySQL database; output depends on its rows.

<?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 database configuration');
$mysqli = new mysqli($host, $user, $password, $database);
$mysqli->set_charset('utf8mb4');
$userId = 5;
$stmt = $mysqli->prepare("SELECT id, email FROM users WHERE id >= ? ORDER BY id");
$stmt->bind_param("i", $userId);
$stmt->execute();
$stmt->close();
echo "Prepared statement closed";

Example 3: Practical Checks

The SELECT assumes users(id,email) in an actual MySQL database; output depends on its rows.

<?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 database configuration');
$mysqli = new mysqli($host, $user, $password, $database);
$mysqli->set_charset('utf8mb4');
$userId = 8;
$stmt = $mysqli->prepare("SELECT id, email FROM users WHERE id >= ? ORDER BY id");
$stmt->bind_param("i", $userId);
$stmt->execute();
$stmt->close();
echo "Prepared statement closed";

Important Behavior and Edge Cases

Do not execute or fetch from the same statement after closing it.

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

• Closes the prepared statement and frees its associated server and client resources.
• Do not execute or fetch from the same statement after closing it.
• reset keeps the statement prepared for another execution; close ends its use.

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.