Question

我在Oracle中有以下查询

select (case when seqnum = 1 then id else '0' end) as id,
       (case when seqnum = 1 then start else "end" end) as timestamp,
       unit
from (select t.*,
             row_number() over (partition by id, unit order by start) as seqnum,
             count(*) over (partition by id, unit) as cnt
      from table t
     ) t
where seqnum = 1 or seqnum = cnt;

而不是选择单位，这是一个数字，我想带来它的描述。描述存储在另一个表中，我正在尝试使用desciption而不是数字。

SELECT t2.unit_description from t2,t where t2.unit = t.unit

我正在尝试加入这些结果，但它无效。在这种情况下，有人可以帮助我吗？

Answer 1

这不起作用吗？

select (case when seqnum = 1 then id else '0' end) as id,
       (case when seqnum = 1 then start else "end" end) as timestamp,
       t2.unit_description
from (select t.*,
             row_number() over (partition by id, unit order by start) as seqnum,
             count(*) over (partition by id, unit) as cnt
      from table t
     ) t
join t2 on t.unit = t2.unit
where seqnum = 1 or seqnum = cnt;

Answer 2

我认为这就是你想要的：

select (case when t.seqnum = 1 then t.id else '0' end) as id,
       (case when t.seqnum = 1 then t.start else t."end" end) as timestamp,
       t.unit,
       t2.unit_description
from (select t.*,
             row_number() over (partition by id, unit order by start) as seqnum,
             count(*) over (partition by id, unit) as cnt
      from table t 
     ) t join
     t2
     on t2.unit = t.unit
where seqnum = 1 or seqnum = cnt;

Answer 3

试试这个：

select (case when seqnum = 1 then id    else 0     end)             as id,
       (case when seqnum = 1 then start else "end" end)             as timestamp,
       (SELECT t2.unit_description from t2 where t2.unit = t.unit)  as unit
  from (select t.*,
               row_number() over (partition by id, unit order by start) as seqnum,
               count(*) over (partition by id, unit) as cnt
          from table t
        ) t
  where seqnum = 1 or seqnum = cnt;

ORACLE - 如何在这种情况下加入[JOIN以外的其他选项]？

3 个答案: