mysqli_query（）期望参数1是mysqli，null给出

Question

我正试图遵循YouTube教程来构建CMS。我开始对它创建的错误消息感到困惑。我得到以下错误 '警告：mysqli_query（）期望参数1为mysqli，null在第7行给出的/home/a8241081/public_html/index.php'

我的代码是否正确？是否应该有一个mysqli_select语句？

<?php 
$db_host = "********"; 
$db_username = "******"; 
$db_pass = "*******"; 
$db_name = "********"; 
mysqli_connect("$db_host","$db_username","$db_pass", "$db_name") or die ("could not connect to mysql"); 
?> 

<?php 
session_start(); 
require_once "scripts/connect_to_mysql.php"; 

//Build Main Navigation menu and gather page data here 
$sqlCommand = "SELECT id, linklabel FROM pages ORDER BY pageorder ASC"; 
$query = mysqli_query($myConnection,$sqlCommand) or die (mysqli_error($myConnection)); 

$menuDisplay=''; 
while ($row=mysqli_fetch_array($query)){ 
    $pid=$row["id"]; 
    $linklabel=$row["linklabel"]; 

    $menuDisplay .='<a href="index.php?pid=' . $pid . '">' . $linklabel . '</a><br/>'; 

    } 
    mysqli_free_result($query); 
    //mysqli_close($myConnection); 
?> 

感谢

Answer 1

你应该有

$myConnection = mysqli_connect($db_host, $db_username, $db_pass, $db_name) or die ("could not connect to mysql"); 

第一区块的结尾。

在你当前的代码$ MyConnection的不在此调用定义：

$query = mysqli_query($myConnection, $sqlCommand) or die (mysqli_error($myConnection));