Oracle：Select 使用子查询中的复合键

Question

情况是这样的——我们的记录使用 name/date 的复合键。我想查看所有连续执行了 2 个特定操作的名称，所以我想做类似

 select name from 
 (select name as n, date as d from table where action='action1'),
 (select name from table where name = n and date > d and action='action2' and rownum=1 order by date desc)

但它将 n 和 d 计为无效标识符。我怎样才能让它做我需要的事情？

Answer 1

一种方法可能是：

SELECT
  a1.name
FROM
  (SELECT name, date FROM table WHERE action = 'action1') a1
JOIN
  (SELECT name, date FROM table WHERE action = 'action2') a2
  ON
  a2.name = a1.name
  AND
  a2.date > a1.date

如果一个名称的每个操作可以有多个实例，这可能会给您重复。在这种情况下，使用 SELECT DISTINCT 来消除重复可能就足够了。

请注意，这并不意味着这两个动作立即接连发生，只是说动作 2 在动作 1 之后的某个时间发生。

Answer 2

分析函数非常适合这类事情....免责声明这是快速而肮脏的，列名有点误导。 LAG/LEAD 是您想要玩的选项

http://sqlfiddle.com/#!4/bd7b2/7

select name,thedate,theaction,prev_action,prev_date from 
 (
 select name,thedate,theaction,
 lag(theaction) over (partition by name order by thedate,theaction) as prev_action,
lag(thedate) over (partition by name order by thedate,theaction) as prev_date
from table1 
order by name,thedate,theaction
)
where theaction = 'action1' and prev_action = 'action2'
;

Oracle：Select 使用子查询中的复合键

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