i want to migrate mysql to mysql

I want to change the database connection from MySQL to mysqli.

Here is my mysql connection code-

function mysql_dbconnect()
{
    $link = @mysql_connect('localhost','root','Z!z@ef!PiV+;');
    if ($link === FALSE){
        $private_error = 'mysql_dbconnect: could not open connection to mysql:'
            .'<li>errno:'.mysql_errno()
            .'<li>error:'.mysql_error()
            ;
        error_log($private_error,0);
        die('Error: could not connect to database server.Please contact the system administrator.');
        exit;
    }

    if (!@mysql_select_db('db')){
        $private_error = 'mysql_dbconnect: could not select database:'
            .'<li>errno:'.mysql_errno()
            .'<li>error:'.mysql_error()
            ;
        error_log($private_error,0);
        die('Error: could not connect to database.Please contact the system administrator.');
        exit;
    }
    return $link;
}

I am new at this. I want to change it to mysqli so that I can change the PHP version to 8.0.

Can anyone please let me know how to change it to mysqli connection?