将utf8mb4更改为utf8

Question

我正在尝试使脚本将我的编码从utf8mb4更改为utf8。

我的PHP knowlege有点过时，我不能让脚本与mysqli一起工作。

这是基本的脚本我有：

<?php 
$con = mysql_connect('localhost','user','password'); 
if(!$con) { echo "Cannot connect to the database ";die();} 
    mysql_select_db('dbname'); 
    $result=mysql_query('show tables'); 
    while($tables = mysql_fetch_array($result)) { 
    foreach ($tables as $key => $value) { 
     mysql_query("ALTER TABLE $value CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci"); 
    }} 
    echo "The collation of your database has been successfully changed!"; 
    ?> 

这是行不通的，所以我尝试更新它的mysqli，现在我有这个：

<?php 
$mysqli = new mysqli("localhost", "root", "", "test"); 

if (mysqli_connect_errno()) { 
    printf("connexion error : %s\n", mysqli_connect_error()); 
    exit(); 
} 

if ($result = $mysqli->query("SELECT DATABASE()")) { 
    $row = $result->fetch_row(); 
    printf("The database is : %s.\n", $row[0]); 
    $result->close(); 
} 

    $result=mysqli_query('show tables'); 
    while($tables = mysqli_fetch_array($result)) { 
    foreach ($tables as $key => $value) { 
     mysqli_query("ALTER TABLE $value CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci"); 
    }} 
    echo "The collation of your database has been successfully changed!"; 
    ?> 

我认为这个问题是在最后一部分，我得到的错误是：

比k你的帮助！ :)

Answer 1

mysqli_query()需要第一个参数作为您的连接。使用它作为

$result = mysqli_query($mysqli, 'show tables'); 
while ($tables = mysqli_fetch_array($result)) { 
    foreach ($tables as $key => $value) { 
     mysqli_query($mysqli, "ALTER TABLE $value CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci"); 
    } 
}