php - mysql_result() 期望参数 1 为资源，给定的字符串

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']} ");