如果所有项目都足够，则更新多个项目数量

Question

我正在开发一个库存系统，其中产品与其原始商品相关联。当用户创建Out Transaction时，应同时扣除产品数量及其原始项目。我想要实现的是仅在所有项目足够时更新数量。我现在面临的问题是当其中一个项目为0时，它仍然会扣除其他项目数量。请帮忙。

以下是我的代码：

//deduct child items if OUT transactions .
            //dont deduct item if nature = stockist
        }elseif (($indicator == 0) && ($nature!=17)){

        $find_child_qry = mysql_query("SELECT * FROM packages p
                                        LEFT JOIN item_balance ib ON ib.item_id=p.item_id
                                        WHERE product_id = '$prod_id'");
        while($res = mysql_fetch_array($find_child_qry)){

            foreach($res as $key => $value) {$res[$key] = stripslashes($value);}
            $qty = $res['quantity']*$_POST['quantity'];
            //$item_id = array($res['item_id']);
            $item_id = $res['item_id'];
            $balance = array($res['balance']);

            if ($qty > (findItemBalance(($item_id)))){

                    //if ($qty > (findItemBalance(($item_id)))){
                echo "<p style='color:red'><strong>Item balance not sufficient: ".findItemName(($res['item_id']))."</strong></p>";


            //}elseif(($qty <= findItemBalance(($res['item_id'])))){
            }else{
            //insert out transaction    
            $sql2 = "INSERT INTO item_transactions (transaction_type_id, date, item_id, quantity, remarks, created_by, created_at)
                VALUES (
                    '8', 
                    '$date',
                    '{$res['item_id']}', 
                    '$qty', 
                    'Deduction from Manage Product {$item_id}', 
                    '$created_by', 
                    '$created_at') ";
                    if(mysql_query($sql2)){

                    //echo mysql_insert_id();
                        echo "<div class='success'>Item OUT Transaction accepted.</div>";
                    }else{
                        echo "<div class='error'>".mysql_error()."</div>";
            }   




            }
}   



            if($_POST['quantity'] <= findProductBalance($prod_id, $created_by)){
            //insert product transaction
            $sql = "INSERT INTO product_transaction (transaction_type_id, date, product_id, quantity, remarks, created_by, created_at)
                VALUES (
                    '{$_POST['transaction_type_id']}', 
                    '$date',
                    '$prod_id', 
                    '{$_POST['quantity']}', 
                    '{$_POST['remarks']}', 
                    '$created_by', 
                    '$created_at') ";

            if(mysql_query($sql)){

            echo "<div class='success'>Transaction accepted.</div>";
            }else{
                echo "<div class='error'>".mysql_error()."</div>";
            }

            }

}else{
                echo "<div class='error'>".mysql_error()."</div>";
            }

Html表格：

<link rel="stylesheet" type="text/css" href="css/listings.css">

<h3><?php echo findProductName($prod_id) ?></h3>
<form name="form1" action="" method="post">
<input type="hidden" name="product_id" value="<?php echo $prod_id ?>" />
<table cellspacing="0">

<tr>
        <th colspan="2">Enter Product Transaction Information</th>
</tr>

<tr>
    <td style='border-left: 1px solid #C1DAD7;'>Select Transaction Type</td>
    <td>
    <select name="transaction_type_id" onchange="ajax(this.value, <?php echo $prod_id ?>);" />  
        <option value="">Please Select</option>     
        <?
            $sql=mysql_query("select * from transaction_types order by name");
            while($row=mysql_fetch_assoc($sql)){
        ?>
            <option value="<? echo $row['id']; ?>"><? echo $row['name']; ?></option>
        <?
            }
            mysql_free_result($sql);
        ?>
    </select>
    </td>
</tr>

<tr>
    <td style='border-left: 1px solid #C1DAD7;'>Transaction Date</td>
    <td>
        <?php DateSelector( "Sample"); ?> 
    </td>
</tr>


<tr id="disp_select"></tr>

<tr>
    <td style='border-left: 1px solid #C1DAD7;'>Quantity</td>
    <td><input type="number" id="quantity" name="quantity" value="<?php echo $_POST['quantity'] ?>" /></td>
    <input type="hidden" id="item_type" name="item_type" />
</tr>

<tr>
    <td style='border-left: 1px solid #C1DAD7;'>Remarks</td>
    <td><input type="text" name="remarks" size="50" value="<?php echo $_POST['remarks'] ?>" /></td>
</tr>

<?php 
if (have_expiry_date($item_id)==1){
    include_once("item_types/_have_expiry_date.php");
}
?>

 </table>

 <br/>
 <input type="submit" id="submit" name="submit" value="Submit" />
 </form>