wordpress database error

I write code to extract peice from website with curl. this should be refresh page to get price.

I want store data in the wordpress database with foreach.

when I refreshing page

but give this error.

Call to a member function insert() on a non-object in C:\wamp\www\wordpress\wp-content\plugins\price\fras-coin.php on line 73

database

   foreach($table_rows as $tr) { // foreach row
 $row = $tr->childNodes;
if($row->item(0)->tagName != 'tblhead') { // avoid headers
    $data[] = array(
         $trip ['Name' ]= trim($row->item(0)->nodeValue),
         $trip['LivePrice'] = trim($row->item(2)->nodeValue),
         $trip ['Changing']=  trim($row->item(4)->nodeValue),
         $trip ['Lowest']=  trim($row->item(6)->nodeValue),
         $trip['Topest']=  trim($row->item(8)->nodeValue),
         $trip['Time']=  trim($row->item(10)->nodeValue),

      );
   }
   }
global $wpdb;
foreach($table_rows as $tr) { // foreach row
$row = $tr->childNodes;
if($row->item(0)->tagName != 'tblhead') { // avoid headers
    $wpdb->insert( $wpdb->farsc, 
    array( 
    'title' => " . trim($row->item(0)->nodeValue) . ",
    'liveprice' => " . trim($row->item(2)->nodeValue) . ",
    'changing' => " . trim($row->item(4)->nodeValue) . ",
    'lowest' => " . trim($row->item(6)->nodeValue) . ",
    'topest' => " . trim($row->item(8)->nodeValue) . ",
    'time' => " . trim($row->item(10)->nodeValue) . " ), 
    array( 
    '%s',
    '%s',
    '%s',
    '%s',
    '%s',
    '%s'
 ) );
    ///$sql = "INSERT INTO `fars_coin`(title,liveprice,changing,lowest,topest,time) VALUES ('" . trim($row->item(0)->nodeValue) . "','" . trim($row->item(2)->nodeValue) . "','" . trim($row->item(4)->nodeValue) . "','" . trim($row->item(6)->nodeValue) . "','" . trim($row->item(8)->nodeValue) . "','" . trim($row->item(10)->nodeValue) . "')";
    /// 
    ///mysql_query($sql);

}

}