计数id唯一的显示

Question

以下代码无效：

<?php 
        $sql = 'SELECT sum(display) AS nb_total FROM tracking where id_site ="'.$id_site.'"';
        $req = mysql_query($sql) or die('Erreur SQL !'.$sql.''.mysql_error());
        $data = mysql_fetch_array($req); 
        echo $data['nb_total']; 
?>

请帮助我

Answer 1

试试这个：

$sql = "SELECT sum(display) AS nb_total FROM tracking where id_site =$id_site";

Answer 2

像这样纠正这条线

$sql = "SELECT sum(display) AS nb_total FROM tracking where id_site ='$id_site'";