Question

希望在总费用超过230之前选择旅游日期和网站名称，并且游览人数超过7人。完整的代码如下，工会的第一部分工作。

SELECT tour_date AS "Departure Date",  site_name "Site Name"
FROM partres, reservation, tour, site
WHERE partres.res_id = reservation.res_id
  AND reservation.tour_id = tour.tour_id
  AND tour.site_id = site.site_id
GROUP BY tour_date, site_name
HAVING COUNT(part_id) > 7

  UNION

SELECT tour_date AS "Departure Date",  site_name "Site Name"
FROM (
  SELECT res_id,tour_date,site_name, (res_partcost +NVL(RES_GEARCOST,0)) as "total_cost" 
  FROM reservation,site,tour) 
WHERE  reservation.tour_id = tour.tour_id
  AND tour.site_id = site.site_id
  AND total_cost > 230
GROUP BY tour_date, site_name;

我仍然有错误

ORA-00904: "TOTAL_COST": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:
Error at Line: 437 Column: 7

由于

Answer 1

您需要在子查询中移动连接条件

SELECT tour_date AS "Departure Date",  site_name "Site Name"
FROM (
    SELECT res_id,tour_date,site_name, (res_partcost +NVL(RES_GEARCOST,0)) as "total_cost" 
    FROM reservation,site,tour
    WHERE reservation.tour_id = tour.tour_id
    AND tour.site_id = site.site_id ) Res1
WHERE Res1.total_cost > 230 // this will not be displayed in a result
GROUP BY tour_date, site_name;

Answer 2

union不会在条件之间给你一个“和”。它会给你一个“或”（因为任何符合任何一个条件的东西都会包括在内）。

我认为你应该将这个短语称为单个查询。此外，正确的连接语法是一个好处：

SELECT tour_date AS "Departure Date",  site_name "Site Name"
FROM partres p join
     reservation r
     on p.res_id = r.res_id join
     tour t
     on r.tour_id = t.tour_id and
        (res_partcost + coalesce(RES_GEARCOST,0)) > 230 join
     site s
     on t.site_id = s.site_id
GROUP BY tour_date, site_name
having COUNT(part_id) > 7;

这个版本猜测total_cost在reservation表中。{/ p>

sql中带有无效标识符错误的子查询

2 个答案: