MySQL错误：``字段列表''中的未知列``变量''

Question

I have got this function that returns a constant..Here is my class and function:

class Backlinks extends GoogleSearch {
const ROBOTS_NOINDEX_NOFOLLOW = 606;

    function robotsNoIndexNoFollow(){
    $crawler = new Connection();
    $curl = $crawler -> setUrl($this->url) ->getDocument();
    if ($curl){
        $html = new simple_html_dom($curl);
        $robots = $html -> find("meta[name=robots]", 0);
        $html -> clear();
        unset ($crawler);
        if ($robots){
            $content = $robots -> getAttribute("content");
            $content = strtolower($content);
            if (substr_count($content, "noindex")){
                return ROBOTS_NOINDEX_NOFOLLOW; 
            }
            if (substr_count($content, "nofollow")){
                return ROBOTS_NOINDEX_NOFOLLOW;
            }
        }
        else{
            return false;
        }
    }

}

The problem above is in the ROBOTS_NOINDEX_NOFOLLOW contatnt. The constant goes into another function as an error parameter to be updated in the database.

public function setStatus($error){
    $status = $error;
    if (!$error){
        $status = 200;
    }
    // only update the pages which weren't already scanned (for historic purposes).
    $query = "UPDATE task_pages tp 
        SET scan_status = $status 
        WHERE page_id = $this->pageID AND scan_status = 0";
    mysql_query($query) or die(mysql_error());
}

I get two errors:

Notice: Use of undefined constant ROBOTS_NOINDEX_NOFOLLOW - assumed 'ROBOTS_NOINDEX_NOFOLLOW' in C:\\Program Files (x86)\\Zend\\Apache2\\htdocs\\backlinks\\cron\\Backlinks.php on line 78 Unknown column 'ROBOTS_NOINDEX_NOFOLLOW' in 'field list'

One is the problem with the constant not being defined..which I dont understand why. The second problem is with the sql..which interprets the constant as a column?!?

Why and how to correct that?

Answer 1

You need qoutes around the string for MySQL to recognise it as data instead of a constant. Try:

"UPDATE task_pages tp 
        SET scan_status = '$status' 
        WHERE page_id = $this->pageID AND scan_status = 0";

Answer 2

You need to use 'self' to reference the constant:

return self::ROBOTS_NOINDEX_NOFOLLOW

Otherwise, PHP would try to find the constant in the global scope even though in your case this is a class constant.