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首页 > 解决方案 > 为什么在 WHERE 子句中使用硬编码值时在 Group BY 语句中出现错误？

php - 为什么在 WHERE 子句中使用硬编码值时在 Group BY 语句中出现错误？

问题描述

我是 PostgreSQL 新手。我正在开发出租车预订应用程序。

我试图找出为什么（1）不起作用。硬编码值将被用户输入替换。

  1. 非工作：

    SELECT MAX(cr.pickup_point) AS Pickup_point, MAX(cr.destination) AS destination, MAX(cr.leave_time) AS leave_time,MAX(cr.license) AS license, MAX(cr.username) AS username, MAX(cr. car_ride_id) AS car_ride_id , MAX(isd.no_of_seats) AS no_of_seats FROM car_ride cr , is_driver isd WHERE cr.username = isd.username AND cr.license = isd.license AND LOWER(TRIM(pickup_point))::varchar = LOWER(TRIM ('东巴耶利峇'))::varchar AND (LOWER(TRIM(cr.destination))::varchar = LOWER(TRIM('Kranji, Sungei Kadut'))::varchar AND (cr.leave_time) > now()::timestamp(0) GROUP BY(cr.car_ride_id, isd.no_of_seats) HAVING isd.no_of_seats> ALL (SELECT COUNT(*) FROM bids b, car_ride cr2 WHERE b.driver_username = cr2.username AND b.成功为真 AND b.leave_time >now()::timestamp(0) AND cr2.leave_time = b.leave_time AND cr。car_ride_id = cr2.car_ride_id)

2.工作：

SELECT  MAX(cr.pickup_point) AS pickup_point , MAX(cr.destination)
AS destination , MAX(cr.leave_time) AS leave_time ,
MAX(cr.license) AS license , MAX(cr.username)
AS username, MAX(cr.car_ride_id) AS car_ride_id , MAX(isd.no_of_seats) AS no_of_seats
FROM car_ride  cr , is_driver isd WHERE cr.username = isd.username
AND cr.license =  isd.license AND
(cr.leave_time)> now()::timestamp(0) GROUP BY(cr.car_ride_id, isd.no_of_seats)  HAVING
isd.no_of_seats>
ALL (SELECT COUNT(*) FROM bids b , car_ride cr2 WHERE
b.driver_username = cr2.username AND b.successful IS TRUE
AND  b.leave_time >now()::timestamp(0) AND cr2.leave_time = b.leave_time
AND cr.car_ride_id = cr2.car_ride_id )

(1.) 和 (2.) 之间的区别在于前者打算根据接送点和目的地过滤结果。

而 (2) 显示所有未来且未完全预订的乘车广告（对于特定的 car_ride_id < car_capacity 的出价数 = TRUE），以便汽车未完全预订。

请注意，我已多次使用 MAX 聚合，因为我已将它们用作后续表单中的隐藏字段以进行投标。

第二次查询的结果

运行第一个查询时出现错误消息。

错误：“GROUP”处或附近的语法错误

第 10 行：分组依据（cr.car_ride_id，isd.no_of_seats）

标签： phpdatabasepostgresqlgroup-byphppgadmin

解决方案

AND您在and之间有一个没有关闭的不必要的括号LOWER：

  AND (LOWER(TRIM(cr.destination))::varchar = LOWER(TRIM('Kranji, Sungei Kadut'))::varchar

固定的：

SELECT MAX(cr.pickup_point) AS pickup_point , MAX(cr.destination) AS destination,
       MAX(cr.leave_time) AS leave_time,MAX(cr.license) AS license ,
       MAX(cr.username) AS username, MAX(cr.car_ride_id) AS car_ride_id ,
       MAX(isd.no_of_seats) AS no_of_seats
  FROM car_ride cr , is_driver isd
 WHERE cr.username = isd.username
   AND cr.license = isd.license
   AND LOWER(TRIM(pickup_point))::varchar = LOWER(TRIM('Paya Lebar East, Paya Lebar'))::varchar
   AND /*(*/LOWER(TRIM(cr.destination))::varchar = LOWER(TRIM('Kranji, Sungei Kadut'))::varchar
   AND (cr.leave_time)> now()::timestamp(0)
 GROUP BY(cr.car_ride_id, isd.no_of_seats)
HAVING isd.no_of_seats> ALL (SELECT COUNT(*)
                               FROM bids b , car_ride cr2
                              WHERE b.driver_username = cr2.username
                                AND b.successful IS TRUE
                                AND b.leave_time >now()::timestamp(0)
                                AND cr2.leave_time = b.leave_time
                                AND cr.car_ride_id = cr2.car_ride_id)

当您以更易读的方式格式化查询时，更容易避免这些错误。

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