我的mysql数据库。

mysql> show variables like 'character%';
+--------------------------+-------------------------------+
| Variable_name            | Value                         |
+--------------------------+-------------------------------+
| character_set_client     | utf8                          |
| character_set_connection | utf8                          |
| character_set_database   | gb2312                        |
| character_set_filesystem | binary                        |
| character_set_results    | utf8                          |
| character_set_server     | utf8                          |
| character_set_system     | utf8                          |
| character_sets_dir       | F:\wamp\mysql\share\charsets\ |
+--------------------------+-------------------------------+

mysql> show variables like "collation%";
+----------------------+-------------------+
| Variable_name        | Value             |
+----------------------+-------------------+
| collation_connection | utf8_general_ci   |
| collation_database   | gb2312_chinese_ci |
| collation_server     | utf8_general_ci   |
+----------------------+-------------------+

我想用php7中的mysqli选择一些信息。名为 getdata1.php 被编码在 utf-8 .

My getdata1.php file.
<?php
    header("Content-type: text/html; charset=utf-8"); 
    $mysqli = new mysqli("localhost", "root", "xxxxxx", "student");
    $sql = "SELECT * FROM student";
    $result = $mysqli->query($sql);
    $row = $result->fetch_assoc();
    print_r($row);
    $result->close();
    $mysqli->close();
?>

我得到了以下输出。

Array ( [ID] => 1 [学号] => 11410104 [姓名] => 陈XX)

据我所知，汉字可以用于php的关联数组的关联键和值。
现在我想用 $row["姓名"] .
使用以下文件 getdata2.php 编码于 utf-8 我也一样，什么都没有。

My getdata2.php file.
<?php
    header("Content-type: text/html; charset=utf-8"); 
    $mysqli = new mysqli("localhost", "root", "xxxxxx", "student");
    $sql = "SELECT * FROM student";
    $result = $mysqli->query($sql);
    while ($row = $result->fetch_row()) {
        printf ("%s \n", $row["姓名"]);
    }
    $result->close();
    $mysqli->close();
?>

检查apache中的日志文件。

Notice:  Undefined index: \xe5\xa7\x93\xe5\x90\x8d in F:\\wamp\\apache2\\htdocs\\getdata2.php on line 7
[Sun Aug 12 20:25:23.217182 2018] [:error] [pid 12204:tid 1264] [client 127.0.0.1:54023]

这个 \xe5\xa7\x93\xe5\x90\x8d 字符串是 姓名 的utf-8编码。

python3
>>> b"\xe5\xa7\x93\xe5\x90\x8d".decode("utf-8")
'姓名'

如何在php7的mysqli查询中使用汉字作为关联键？