Question

练习39：定义“为未来的战斗而存活”的船只; 他们在一场战斗中受伤，参加了另一场战斗。

数据库架构：http://www.sql-ex.ru/help/select13.php#db_3

我的方法：

SELECT distinct o.ship from Outcomes o
WHERE o.RESULT = 'damaged' 
AND exists (select 1 FROM Outcomes o2 WHERE o2.ship = o.ship 
AND (o2.result='OK' OR o2.result='sunk'))

sql-ex说

您的查询在主数据库上生成了正确的结果集，但失败了第二次测试，检查数据库

正确的结果与我的输出匹配。

我失败的地方？

Answer 1

解决！需要添加Distinct

select distinct kk.ship from
(Select ship,date from outcomes oo,battles bb where oo.battle=bb.name) tt 
inner join 
(Select ship,date as damagedate from outcomes oo,battles bb where result='damaged' AND oo.battle=bb.name) kk 
ON tt.ship=kk.ship AND tt.date>kk.damagedate

Answer 2

with a as (select * from outcomes o join battles b on o.battle=b.name)select distinct a1.ship from a a1, a a2 where a1.ship=a2.ship and a1.result='damaged'and a1.date<a2.date

Answer 3

试试这个：

    select o.ships from (select a.ships, a.battle from outcomes as a where result in (damaged, unharmed)) as o
    where o.battle <> a.battle

Answer 4

select distinct outcomes.ship
from outcomes, (select outcomes.ship, battles.[date], outcomes.result
            from outcomes, battles
            where battles.name = outcomes.battle
            and result = 'damaged' ) t1, 
 battles
where outcomes.ship = t1.ship and
outcomes.battle = battles.name and
battles.[date] > t1.[date]

Answer 5

这是我的答案，并没有在页面上解析为真，但我不同意。不知道我的解决方案与你的解决方案有什么不同

select distinct damaged.ship from 
(Select oo.ship,date from outcomes oo
inner join battles bb on oo.battle=bb.name
) as ships
inner join (Select ship,date as damagedate from outcomes oo1
inner join battles bb1 on oo1.battle=bb1.name and result = 'damaged') as damaged
on (ships.ship = damaged.ship and ships.date != damaged.damagedate)

Answer 6

也许这不是最棒的设计，但对我也有用：

with damaged as (Select b.date, o.ship
from outcomes o 
inner join battles b on b.name = o.battle
where result = 'damaged') 

Select distinct o.ship
from outcomes o 
right join damaged d on d.ship = o.ship
right join battles b on b.name = o.battle
where b.date > d.date

sql-ex exercise 39在第二次服务器错误时失败了吗？

6 个答案: