遍历整个table，并将满足内部查询的所有值传递给外部查询

Question

--Pass each of the pmi value from the below query to an outer query.
select pmi 
from support
where supportid = (select supportid 
                   from support 
                   where pmi = '123'
                   order by datereceived DESC
                   fetch first 1 row only)
  and reason ='XYZ'

我的 table support 中的特定 pmi 有多行。对于每组 pmi，我需要使用 datereceived 列找到最新的行，然后检查该最新的行是否有原因 'XYZ'.

仅当原因是最新行中的 'XYZ' 时，我才必须将 pmi 值传递给外部查询。

如果我将 pmi 硬编码到内部查询中，它会起作用，但我希望内部查询遍历 table 中的所有 pmi。

如有任何帮助，我们将不胜感激。

Answer 1

这就是分析函数的用途：

SELECT *
FROM (SELECT pmi, 
             supportid, 
             datereceived, 
             reason, 
             MAX(datereceived) OVER (PARTITION BY pmi) AS MAX_DATE
      FROM support) s
WHERE s.datereceived = s.max_date
AND s.reason = 'XYZ';

Answer 2

您根本不需要子查询。只需按 pmi 聚合并使用 KEEP LAST 检查最后一行的原因是否为 XYZ:

select pmi
from support
group by pmi
having max(reason) keep (dense_rank last order by datereceived) = 'XYZ';

不过，

KEEP LAST 是 Oracle 专有的。如果您想要更接近您自己的查询（并且符合标准），您可以使用：

select pmi 
from support
where (pmi, datereceived) in
(
  select pmi, max(datereceived)
  from support 
  group by pmi
)
and reason = 'XYZ';

Answer 3

Throsten 的回答很好。使用标准 SQL 和聚合的替代方法是：

select pmi
from support
group by pmi
having max(datereceived) = max(case when reason = 'XYZ' then datereceived end);

即 return 所有 pmi 其中 'XYZ' 上的日期是最后一个日期。

遍历整个table，并将满足内部查询的所有值传递给外部查询

Iterating over the entire table, and passing all values that satisfies an inner query to an outer query

sql

oracle

plsql

oracle10g

oracle11g