mysql_result（）預計參數1是資源，字符串中給定

Question

的錯誤是在$quant=mysql_result($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

那是因爲你沒有實際查詢數據庫。

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

應該

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

Answer 2

試試這個>>

---

$quantity=mysql_query("SELECT product_qty_available FROM product WHERE product_id={$_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; 
    } 

試試這個，這將工作。