使用mysql_result PHP从MySQL迁移到MySQLi

Question

So initially, I know that using the MySQL extension is not good for security and it's not updated but I only had used it for learning but now I want to move to MySQLi and I am not sure how I can convert it. I have two problems and I am not sure where to go as you can see below for the first set of code.

What I want to do is check if a server is active and this is defined in a database where the table looks like this

So if active is equal to 1 then that is true , if not then it should be false .

function server_active_query($data) {
    $server = sanitize($data);
    $query = mysql_query("SELECT COUNT(`server_id`) FROM `servers` WHERE `servername` = '$server' AND `active` = 1"); 
    return (mysql_result($query, 0) == 1) ? true: false;
}

//This is the new function so don't worry about the name
function server_active_query($data) {
    $dbc = new mysqli('db_host', 'db_user', 'db_pass', 'db_db');
    $server = sanitize($data, $dbc);
    $query = $dbc->query("SELECT COUNT(`s_id`) FROM `servers` WHERE `servername` = '$server' AND `active` = 1"); 
    //Not sure where to go from here as It does not work.
    return (mysqli_result($query, 0) == 1) ? true: false;
}

Answer 1

You need to stick with the OO mysqli calls and the one you are looking for is $result->num_rows which returns the number of rows returned by the SELECT query.

Using ->query() returns a mysqli_result object and that does not have the ability to return you the data from column 0 like the the mysql_ extensions does, so change the query to select a field, so it only returns a row if it find a server in the active state, then you can use the ->num_rows property

function server_active_query($data) {
    $dbc = new mysqli('db_host', 'db_user', 'db_pass', 'db_db');
    $server = sanitize($data, $dbc);

    $result = $dbc->query("SELECT `s_id` 
                           FROM `servers` 
                           WHERE `servername` = '$server' AND `active` = 1"); 

    return $result->num_rows == 1 ? true: false;
}

Or to use the better prepare() style

function server_active_query($data) {
    $dbc = new mysqli('db_host', 'db_user', 'db_pass', 'db_db');
    $server = sanitize($data, $dbc);

    $stmt = $dbc->prepare("SELECT s_id
                           FROM servers 
                           WHERE servername = ? 
                             AND active = 1"); 

    $stmt->bind_param("s", $server);
    if ( $stmt->execute() ) {
       $return = $stmt->num_rows == 1 ? true: false;
    } else {
       // error processing code or just default to false?
       $return = false
    }

    // as we have not actually processed the returned row 
    // we had better clean up the statement handle
    $stmt->close(); 

    return $return;
}