Php 在添加时更新现有产品尺寸的库存

我的代码怎么了？产品库存正在更新，但在我按下添加按钮并重新加载页面后，我添加的产品库存将消失

我的问题是：

if(isset($_POST['product_id'])) {
    $product_price = mysqli_real_escape_string($db_conn, $_POST['product_price']);
    $product_stocks = mysqli_real_escape_string($db_conn, $_POST['product_stocks']);
    $product_size =mysqli_real_escape_string($db_conn, $_POST['product_size']);
    $product_id = mysqli_real_escape_string($db_conn, $_POST['product_id']);

    $search_query = "SELECT * FROM tblproduct_extension WHERE product_size = '$product_size'";
    $query = mysqli_query($db_conn, $search_query);
    $exists = mysqli_num_rows($query);

    if($exists) {
        $update_query = "UPDATE tblproduct_extension SET product_stocks = product_stocks + $product_stocks WHERE product_id = '$product_id' AND product_size = '$product_size'";
        $query = mysqli_query($db_conn, $update_query);
    } else {
        $insert_query = "INSERT INTO tblproduct_extension (product_stocks, product_price, product_size, product_id)VALUES('$product_stocks', '$product_price', '$product_size', '$product_id')";
        $query = mysqli_query($db_conn, $insert_query);
    }
}

阿贾克斯

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在选择查询中，您还必须指定产品id。因此，对于您正在搜索的产品，您将得到正确的结果

所以改变

$search_query = "SELECT * FROM tblproduct_extension WHERE product_size = '$product_size'";

到

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问题是，一旦你添加了一个股票，大小和价格。产品将消失。

$search_query = "SELECT * FROM tblproduct_extension WHERE product_size = '$product_size'";

$search_query = "SELECT * FROM tblproduct_extension WHERE product_id = '$product_id' AND product_size = '$product_size'";