mysql_result（）期望参数1是资源，给定字符串

Question

错误在$quant=mysql_result($quantity, 0);

$quantity=("SELECT product_qty_available FROM product WHERE product_id={$_POST['id']} ");
$quant=mysql_result($quantity, 0);


if($quant > $_POST['quant'])
{
  echo "Input Quantity Exceeded!";

}
else
{
  exit;
}

Answer 1

那是因为你实际上并没有查询你的数据库。

$quantity=("SELECT product_qty_available FROM product WHERE product_id={$_POST['id']} ");

应该是

$quantity=mysql_query("SELECT product_qty_available FROM product WHERE product_id={$_POST['id']} ");

Answer 2

试试这个＆gt;＆gt;

---

$quantity=mysql_query("SELECT product_qty_available FROM product WHERE product_id={$_POST['id']} ");

$quant = mysql_result($quantity, 0);

if (!$quant) {
    die('Could not query:' . mysql_error());
    }
if($quant > $_POST['quant'])
{
  echo "Input Quantity Exceeded!";

}
else
{
  exit;
}

Answer 3

 $quantity=mysql_query("SELECT product_qty_available FROM product WHERE product_id='"$_POST['id']."'") or die('Could not query:' . mysql_error());
   // $quant = mysql_result($quantity);
    if(mysql_num_rows($quantity) > $_POST['quant'])
    {
      echo "Input Quantity Exceeded!";
    }
    else
    {
      exit;
    }

试试这个会起作用。