使用单个查询获取多个 table 列的总和

Question

我有一个主要的 table hotel 及其子 tables hotel_food, hotel_extras, hotel_room 参考 ID hotel,

现在我想获得每家酒店的每个 table（hotel_food、hotel_extras、hotel_room）价格列的总和。

现在我是这样用的

$result = $db->query("SELECT id FROM hotel WHERE id = '.$hotel.'");
if($row = $result->fetch_array(MYSQLI_ASSOC)) {
   $food_result = $db->query("SELECT sum(price) FROM hotel_food WHERE hotel_id = '".$row['id']."'");
   $room_result = $db->query("SELECT sum(price) FROM hotel_room WHERE hotel_id = '".$row['id']."'");
   $extras_result = $db->query("SELECT sum(price) FROM hotel_extras WHERE hotel_id = '".$row['id']."'");
}

有什么方法可以通过单个查询获得所有 tables 价格的总和，例如 totalFoodPrice、totalRoomPrice、totalExtrasPrice

提前致谢

Answer 1

SELECT * FROM
(
 SELECT sum(price) AS totalFoodPrice FROM hotel_food WHERE hotel_id = 1,
 SELECT sum(price) AS totalRoomPrice FROM hotel_room WHERE hotel_id = 1,
 SELECT sum(price) AS totalExtrasPrice FROM hotel_extras WHERE hotel_id = 1
) temp

Answer 2

您可以像这样使用子查询：

$result = $db->query("SELECT id, 
   (SELECT sum(price) FROM hotel_food WHERE hotel_id = h.id) TotalFoodPrice,
   (SELECT sum(price) FROM hotel_room WHERE hotel_id = h.id) TotalRoomPrice,
   (SELECT sum(price) FROM hotel_extras WHERE hotel_id = h.id) TotalExtraPrice
FROM hotel h WHERE id = '.$hotel.'");

使用单个查询获取多个 table 列的总和

Get sum of more than one table columns with a single query

php

mysqli