Question

我现在有这个循环，但它涉及调用数据库5到10次。有没有一种方法可以称之为一次，可能是一个while循环，或任何其他任何人都可以想到的替代方案，因为它会减慢行动。

foreach($_SESSION['cart_array'] as $each_item) {
   $item_id = $each_item['item_id'];
   $each_quantity = $each_item['quantity'];
   $item_qry = mysql_query("SELECT * FROM `products` WHERE `products_id`=$item_id");
   $item_row = mysql_fetch_assoc($item_qry);
   $product_price = $item_row['products_price'];
   $total_price += $product_price * $each_quantity;
}

Answer 1

是的，您可以一次选择所有行：

$total_price = 0;
if (!empty($_SESSION["cart_array"])) {
    $query = "SELECT `products_price`, `products_id` FROM `products` WHERE `products_id` IN (";
    $query .= implode(", ", array_map(function ($item) { return $item["item_id"]; }, $_SESSION['cart_array']));
    $query .= ")";
    $result = mysql_query($query);

    while ($row = mysql_fetch_assoc($result))
        $items[$row["products_id"]] = $row["products_price"];

    foreach ($_SESSION["cart_array"] as $item)
        $total_price += $item["quantity"] * $items[$item["item_id"]];
}

Answer 2

一个查询解决方案：

$item_id_array = array();
$item_to_quant = array();
foreach($_SESSION['cart_array'] as $each_item)
{
    $item_id_array[] = $each_item['item_id'];

    $item_to_quant[$each_item['item_id']] = $each_item['quantity'];
}

$item_qry = mysql_query("SELECT * FROM `products` WHERE `products_id` IN (" . implode(',', $item_id_array) . ")");


$total_price = 0;
$results     = array();

while ($item_row = mysql_fetch_assoc($item_qry))
{
    //add total price to result array
    $item_row['total_items_price'] = $item_row['products_price'] * $item_to_quant[$item_row['products_id']];

    $results[] = $item_row;

    $total_price += $item_row['total_item_price'];
}

您将结果数组和总价格变量视为结果。

将foreach更改为while循环以保存mysql查询

2 个答案: