mysql - 警告 mysql_fetch_assoc () 期望参数 1 是 mysqli_result 布尔值

Question

require('includes/database.php');
$db = new Database();
echo "<table border = 1 width=100%>
<tr>
<th> ID </th>
<th> Login ID </th>
</tr>";


$result = $db->select('test','*');
foreach($result as $row)
{
        /*$ID = $row['SID'];
        $fname = $row[First_Name];
        $lname = $row[Last_Name];
        $pwd = $row[Password];
        $email= $row[Email];*/              

        echo "<tr>";
        echo "<td align='center'>". $row['ID'] ."</td>";
        echo "<td align='center'>". $row['Name'] ."</td>";
        echo "</tr><br>";
}

上面的代码给了我警告“警告mysql_fetch_assoc（）期望参数1是mysqli_result boolean给出”但是如果我在select语句中将表替换为“system_user”它对我来说很好。请指教！