在Oracle中如何在同一列上搜索子条件

Question

在Oracle中，如何找到必须具有Feature1并且至少具有Feature2或Feature3中的一个的Cars。样本表和预期结果应如下面的屏幕截图所示。谢谢Kiran

Answer 1

这应该有效：

select t1.car, t1.feature
from yourtable t1
inner join
(  -- inner select returns the cars with the Feature1 and Feature2 or Feature3
  select car, feature
  from yourtable 
  where feature = 'Feature1'
    and exists (select car
                from yourtable 
                where feature in ('Feature2', 'Feature3'))
) t2
  on t1.car = t2.car
where t1.feature in ('Feature1', 'Feature2', 'Feature3') -- this excludes any other features

请参阅SQL Fiddle with Demo

Answer 2

我喜欢使用GROUP BY和HAVING：

select car
from t
group by car
having max(case when feature = 'Feature1' then 1 else 0 end) = 1 and
       max(case when feature in ('Feature1', 'Feature2') then 1 else 0 end) = 1

此查询返回汽车。为了获得这些特色，你必须加入以下：

select t.*
from (select car
      from t
      group by car
      having max(case when feature = 'Feature1' then 1 else 0 end) = 1 and
             max(case when feature in ('Feature1', 'Feature2') then 1 else 0 end) = 1
     ) c join
     t
     on t.car = c.car

我喜欢这种方法，因为同样的想法可用于处理许多不同的类似查询 - AND条件，OR条件，不同的子组和不同的计数。