Question

我试图使用连接查询从多个表中获取一些数据。我有一张预订表，用于存储＆＃34;接送地点ID＆＃34;和＆＃34;删除位置ID＆＃34;和另一张表＆＃34; location＆＃34;存储位置名称的位置。我试图从＆＃34;位置＆＃34;中的2个不同变量中获取位置名称（提取和放置位置）。来自预订表的这两个ID表。

我的表格包含以下参数。位置表：＆＃34; locations_deatils＆＃34;具有location_name location_id。预订表：reservation_cars有pickup_location id，drop_location id，pick_up date，drop_date

SELECT l.location_name as pick-up_loc, 
       l.location_name as drop_loc, 
       c.pickup_date, 
       c.return_date, 
FROM locations_deatils l inner join 
     reservation_cars c on l.locations_id = c.pickup_location and l.locations_id 
= c.return_location 
WHERE c.pickup_date >= :pickupTime and c.return_date <=:returnTime;

Answer 1

也许你的意思是这样的：

SELECT p_loc.location_name AS pickup_location,
       cars.pickup_date,
       d_loc.location_name AS drop_location,
       cars.return_date
FROM   reservation_cars cars
JOIN   location_details p_loc
  ON   cars.pickup_location = p_loc.location_id
JOIN   location_details d_loc
  ON   cars.return_location = d_loc.location_id
WHERE  .....

如果尚未设置取件和/或退货地点，您可能需要使用outer join。

Answer 2

您需要为接送和放置位置单独加入。

SELECT l1.location_name as 'pick-up location', l2.location_name as 'drop location', pickup_date, return_date
FROM reservation_cars r
JOIN locations_deatils l1 ON l1.locations_id = r.pickup_location
JOIN locations_deatils l2 ON l2.locations_id = r.return_location
WHERE r.pickup_date >= :pickupTime 
  AND r.drop_date <= :returnTime

在sql中使用条件检查连接查询

2 个答案: