<?php

$db_host = '127.0.0.1';
$db_user = 'root';
$db_pass = '';
$db_name = 'mysql';

$conn = mysqli_connect($db_host, $db_user, $db_pass, $db_name);

/*
 * A simple query works
 * Entry created in performance_schema.events_statements_summary_by_digest
 * DIGEST_TEXT: SELECT * FROM `mysql` . `user`
 */
$conn->query('SELECT * FROM mysql.user');

/*
 * SQL prepared statements also work
 * Entries created in performance_schema.events_statements_summary_by_digest
 * DIGEST_TEXT: PREPARE `stmt` FROM ?
 * DIGEST_TEXT: EXECUTE `stmt`
 * DIGEST_TEXT: DROP PREPARE `stmt`
 */
$conn->query('PREPARE stmt FROM "SELECT * FROM mysql.user"');
$conn->query('EXECUTE stmt');
$conn->query('DROP PREPARE stmt');

/*
 * C API statements do not work
 * No entry created in performance_schema.events_statements_summary_by_digest
 */
$stmt = $conn->stmt_init();
$stmt->prepare('SELECT * FROM mysql.user');
$stmt->execute();
$stmt->close();