Question

我遇到分层查询问题，以下查询在Oracle中有效，但在DB2

中没有

如果我们从芝加哥开始旅程，它将检索目的地。

SELECT   origin, departure, arrival
FROM  schema001."FLIGHTS"
START WITH departure = 'Chicago'
CONNECT BY PRIOR arrival = departure;

任何人都可以帮助我，我们如何在DB2中编写查询

先谢谢拉杰什

Answer 1

您可以使用递归公用表表达式。

这样的事情：

with ftree (origin, departure, arrival) as (
   select origin, 
          departure, 
          arrival
   from flights
   where departure = 'Chicago'
   union all
   select c.origin,
          c.departure,
          c.arrival
   from flights c
      join ftree p on c.arrival = p.departure
)
select *
from ftree;

（未经测试，现在没有DB2手头）

Answer 2

干杯......我得到了解决方案，工作解决方案是......

WITH rajesh(departure, arrival) AS 
(
select departure, arrival from ALERTS_TEST.flights where departure = 'Chicago'
    UNION ALL
select nplus1.departure, nplus1.arrival  from ALERTS_TEST.flights as nplus1, rajesh
    WHERE rajesh.arrival = nplus1.departure
) 
SELECT departure, arrival FROM rajesh;

我在db2 v9.7和sqlserver 2005中检查了上述查询。它工作得很好...... 感谢您的帮助a_horse_with_no_name

Answer 3

您没有提到正在运行的操作系统。

在IBM i OS 7.1 上运行的DB2 for i 有hierarchical queries，但语法略有不同。

SELECT   origin, departure, arrival
  FROM  schema001.FLIGHTS
  START WITH departure = 'Chicago'
  CONNECT BY arrival = PRIOR departure;

不幸的是，我认为这不适用于DB2 for LUW或z / OS。也许在将来的版本中。

先前为DB2连接

3 个答案: