php数据库连接错误[关闭]

I am trying to connect my PHP code to my sql backend, and I am coming across and error saying "Warning: mysqli_query() expects parameter 1 to be mysqli, string given in - on line 23 Error querying database."

I am following this guide. https://coolestguidesontheplanet.com/how-to-connect-to-a-mysql-database-with-php/

$link = mysqli_init();
$success = mysqli_real_connect(
   $link, 
   $host,
   $user, 
   $password, 
   $db,
   $port,
   $socket
) or die("error");


$query = "select * from Account_data";
mysqli_query($db, $query) or die('Error querying database.');

The first section(up to mysqli_querry) of the code works. However the syntax of the lines appears to be correct compared to the guide.

Any ideas?

Thanks in advance.

As the documentation indicates, in procedural style, the first parameter must be of type mysqli. That is:

$link = mysqli_init();
$success = mysqli_real_connect(
   $link, 
   $host,
   $user, 
   $password, 
   $db,
   $port,
   $socket
) or die("error");


$query = "select * from Account_data";
mysqli_query($link, $query) or die('Error querying database.');