<?php

$db = mysqli_connect("127.0.0.1", "root", "", "test");

$query = "SELECT user FROM mysql.user WHERE user = 'root\0' OR SLEEP(100)";

$db->query($query);

?>

> show full processlist;

+----+-------------+-----------------+------+---------+------+--------------------------+------------------------------------------------+----------+

| Id | User        | Host            | db   | Command | Time | State                    | Info                                           | Progress |

+----+-------------+-----------------+------+---------+------+--------------------------+------------------------------------------------+----------+

[...]

| 17 | root        | localhost:41928 | NULL | Query   |    0 | Init                     | show full processlist                          |    0.000 |

| 18 | root        | localhost:41930 | test | Query   |    2 | User sleep               | SELECT user FROM mysql.user WHERE user = 'root |    0.000 |

+----+-------------+-----------------+------+---------+------+--------------------------+------------------------------------------------+----------+

Time                Id Command  Argument

# Time: 190902 12:22:03

# User@Host: root[root] @ localhost [127.0.0.1]

# Thread_id: 18  Schema: test  QC_hit: No

# Query_time: 300.028394  Lock_time: 0.001831  Rows_sent: 0  Rows_examined: 3

# Rows_affected: 0  Bytes_sent: 70

use test;

SET timestamp=1567419723;

SELECT user FROM mysql.user WHERE user = 'root^@' OR SLEEP(100);