比較輸入數量值和數據庫數量值

Question

我想比較用戶的輸入值和數據庫中的值。如果用戶的輸入值高於數據庫值，則警報窗口將通知用戶他想要的數量不夠。

我該怎麼做？

這裏是我的HTML和PHP代碼

<div class="text">Enter Product Name Here: </div> <br/> 

    <form action="addorder.php" method="post" name="abc"> 

     <a href="auto.php?id=64">BEER</a> 
     <a href="auto.php?id=5">Pizza</a> 
     <a href="auto.php?id=57">Egg Pie</a> 
     <a href="auto.php?id=63">Ice Tea</a> 
     <a href="auto.php?id=66">Combo</a> 

    </div> <br/> <br/> 


      <?php 
       if (isset($_GET['id'])) 
        { 
        $con = mysql_connect('localhost','root',""); 
         if (!$con) 
         { 
          die('Could not connect: ' . mysql_error()); 
         } 

        mysql_select_db("inventory", $con); 

         $member_id = $_GET['id']; 
         $result = mysql_query("SELECT * FROM productlist WHERE id = $member_id"); 
         $row = mysql_fetch_array($result); 
         $name=$row["pdesc"]; 
         $qty_left=$row["pleft"]; 
         $price=$row["pprice"]; 
         $id=$row["id"]; 
         $prcoede=$row["pcode"]; 

        mysql_close($con); 
        } 
      ?> 

<div class="order"> 
<table> 
    <tr> 
     <td><label>Product Name</label></td> 
     <td><label>Product Price </label></td> 
     <td><label>Quantity Left </label></td> 
    </tr> 

    <tr> 
     <td><input name="PNAME" type="text" id="pname" value="<?php echo @$name ?>" size="20" readonly="readonly" /></td> 
     <td><input name="PPRICE" id="PPRICE" type="text" value="<?php echo @$price ?>" readonly="readonly" /></td> 
     <td><input name="AQTY" type="text" value="<?php echo @$qty_left ?>" size="20" readonly="readonly"/></td> 
     <td><input name="id" type="hidden" value="<?php echo $id; ?>" readonly="readonly" /></td> 
     <td><input name="procode" type="hidden" value="<?php echo $prcoede; ?>" readonly="readonly" /></td> 
     <td><input name="less" type="hidden"/></td> 
    </tr> 

     <tr><td></td></tr><tr><td></td></tr> 
     <tr><td></td></tr><tr><td></td></tr> 

    <tr class="space"> 
     <td><label>Reciept Code</label></td> 
     <td><label>Quantity</label></td>  
     <td><label>Amount</label></td> 
    </tr> 

    <tr>   
     <td><input name="CODE" type="text" id="CODE" value="<?php echo $_SESSION['SESS_MEMBER_ID']; ?>" size="20" readonly="readonly"/></td> 








------->  <td><input name="QTY" id="QTY" type="text" onkeyup="multiply()" onkeypress="return checkIt(event)" size="20" /></td> 


      <?php 
       $con = mysql_connect("localhost","root", ""); 
       mysql_select_db("inventory"); 

      $qty = $_POST['QTY']; 

      $a = "SELECT pleft from productlist WHERE pdesc = $qty "; 

      $results = mysql_query($a); 

      if ($qty > $a) 
      { 
       echo '<script type="text/javascript">'; 
        echo 'alert("WARNING: Product not enough ");'; 
        echo 'window.location.href = "auto.php";'; 
       echo '</script>'; 
      } 


?> 








     <td><input name="TOTAL" id="TOTAL" type="text" size="20" readonly="readonly"/></td> 
    </tr> 

    <tr> 
     <td> 
      <div class="cart"> 
       <input name="submit" type="submit" value="Add to Cart" id="xx" style="cursor:pointer; margin-left: 230px; margin-top: 20px;" /> 
      </div> 
     </td> 
    </tr> 
</table> 
</div> 
</form> 
</form> 

Answer 1

  <form action="addorder.php?id=<?php echo $_GET['id'] ? $_GET['id'] : 0?>" method="post" name="abc"> 

        <a href="auto.php?id=64">BEER</a> 
        <a href="auto.php?id=5">Pizza</a> 
        <a href="auto.php?id=57">Egg Pie</a> 
        <a href="auto.php?id=63">Ice Tea</a> 
        <a href="auto.php?id=66">Combo</a> 


        <td><input name="QTY" id="QTY" type="text" onkeyup="multiply()" onkeypress="return checkIt(event)" size="20" /></td> 


         <?php 
         if(!empty($_POST['QTY'])){ 

          $con = mysql_connect("localhost","root", ""); 
          mysql_select_db("inventory"); 

          $qty = $_POST['QTY']; 

          $a = "SELECT pleft from productlist WHERE pdesc = $qty wherer productlist.id = ".$_GET['id']; 




          $results = mysql_query($a); 
          $row = mysql_fetch_assoc($results); 

          if ($qty > $row[0]['pleft']) 
          { 
           echo '<script type="text/javascript">'; 
            echo 'alert("WARNING: Product not enough ");'; 
            echo 'window.location.reload()'; 
           echo '</script>'; 
          }else{ 
          /** 
          Do what ever you want 
          */ 

          } 

         } 


      ?> 

檢查productlist表中有一個名爲id