显示两个价目表之间的差异
我有产品价格的历史列表（按created_at排序），如下所示：
Array
(
[0] => stdClass Object
(
[id] => 1
[product_id] => 49
[price] => 14520000.0000
[created_at] => 1592501154
)
[1] => stdClass Object
(
[id] => 2
[product_id] => 49
[price] => 14000000.0000
[created_at] => 1592587554
)
[2] => stdClass Object
(
[id] => 4
[product_id] => 49
[price] => 14800000.0000
[created_at] => 1592673954
)
[3] => stdClass Object
(
[id] => 5
[product_id] => 49
[price] => 10000000.0000
[created_at] => 1592760354
)
[4] => stdClass Object
(
[id] => 6
[product_id] => 49
[price] => 14000000.0000
[created_at] => 1592846754
)
[5] => stdClass Object
(
[id] => 7
[product_id] => 49
[price] => 14000000.0000
[created_at] => 1592933154
)
[6] => stdClass Object
(
[id] => 8
[product_id] => 49
[price] => 14000000.0000
[created_at] => 1593019554
)
)
现在，为了在表中显示数据，我使用foreach如下方法列出了价格：
<?php foreach($product_prices_list as $product_price_list):?>
<tr>
<td><?= esc($product_price_list->created_at);?></td>
<td class="text-center"><?= esc(number_format($product_price_list->price));?></td>
<td class="text-center"></td> //show difference between of two price
</tr>
<?php endforeach;?>
我可以在表中看到真实的输出，但我需要在第三列中显示两个价格之间的差异，如下图所示：
我如何显示列表中两个价格之间的差异？！
青春有我2回答
-
ITMISS
您只需将当前价格属性与数组中前一个对象的价格进行比较？像这样的东西应该有效：<?php foreach($product_prices_list as $key => $product_price_list):?> <tr> <td><?= esc($product_price_list->created_at);?></td> <td class="text-center"><?= esc(number_format($product_price_list->price));?></td> <td class="text-center"><?= (!empty($product_prices_list[$key - 1])) ? $product_prices_list[$key + 1]->price - $product_price_list->price: 0; ?></td> //show difference between of two price </tr><?php endforeach;?> -
慕田峪4524236
如果您运行的是 MySQL 8.0，则可以使用窗口函数直接在数据库中计算此信息：select t.*, price - lag(price, 1, price) over(partition by product_id order by created_at) as price_difffrom mytable t这会向结果集中再添加一列，其中包含同一产品的当前价格与之前价格之间的差异。
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