mysqli提供了异步执行sql的功能，类似于select轮询机制。先提交SQL到预发布，再去轮询查询是否ok。query的时候加上MYSQLI_ASYNC选项，query就直接提交到mysql，但是本身不等待执行结果。mysqli不亏是加强版的mysql扩展，可惜不是pdo

<?php
/**

• 执行SQL
• @param $sql
• @return mysqli

*/
function query($sql)
{

// 1.创建连接
$servername = "localhost";
$username = "root";
$password = "root";
$database = "test";
$conn = new mysqli($servername, $username, $password, $database);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 2.异步提交SQL
$conn->query($sql, MYSQLI_ASYNC);

// 3.返回SQL连接
return $conn;

}

// 1.保存全部的Conn变量
$all_conn = [];

// 2.循环提交异步SQL
$i = 4;
while ($i--) {

$sql = "select scenes_name_cn from erp_allocation_scenes where id = $i";
$all_conn [] = query($sql, MYSQLI_ASYNC);

}

// 3.循环等待全部的结果
$allResult = [];
do {

$links = $errors = $reject = $all_conn;
if (!mysqli_poll($links, $errors, $reject, 1)) {
    continue;
}
foreach ($all_conn as $conn) {
    if ($result = $conn->reap_async_query()) {
        $allResult[] = $result->fetch_row();
        if (is_object($result)) {
            $result->free();
        }
    } else {
        throw new mysqli_sql_exception(sprintf("MySQLi Error: %s", mysqli_error($conn)));
    }
}

} while (count($allResult) == 5);

// 4.输出查询结果
print_r($allResult);