与 CONNECT_BY_ROOT 的左外连接

Question

我有

SELECT 
  CONNECT_BY_ROOT TAXY.IDCATEGORY AS IDBRANCH
  , TAXY.IDCATEGORY
  , TAXY.IDPARENTCATEGORY
  , TAXY.IDCONTENT
  , TAXY.CATEGORYNAME
  , LEVEL AS LVL
FROM TAXONOMY TAXY
CONNECT BY TAXY.IDCATEGORY = PRIOR TAXY.IDPARENTCATEGORY

并希望将 table CONTENT.

中的每个条目添加到 CONTENTNAME 列

我试过：

SELECT 
  CONNECT_BY_ROOT TCT.CONTENTNAME AS ENDNODECONTENTNAME
  , TAXY.IDCATEGORY
  , TAXY.IDPARENTCATEGORY
  , TAXY.IDCONTENT
  , TCT.CONTENTNAME 
  , TAXY.CATEGORYNAME
  , LEVEL AS LVL
FROM TAXONOMY TAXY
LEFT OUTER JOIN CONTENT TCT ON TCT.IDCONTENT = TAXY.IDCONTENT
CONNECT BY TAXY.IDCATEGORY = PRIOR TAXY.IDPARENTCATEGORY

期望相同的结果，只是 CONNECT_BY_ROOT 使用 1 个额外的列：CONTENTNAME 来自 CONTENT，由 IDCONTENT 关联；如果没有关联内容，则应为 NULL（IDCONTENT 为 NULL）

相反，我只得到 IDCONTENT 不是 NULL 的行。我该怎么做才能获得这些行？

我也试过：

SELECT 
  CONNECT_BY_ROOT TAXY.IDCATEGORY AS IDBRANCH
  , TAXY.IDCATEGORY
  , TAXY.IDPARENTCATEGORY
  , TAXY.IDCONTENT
  , TCT.CONTENTNAME 
  , TAXY.CATEGORYNAME
  , LEVEL AS LVL
FROM TAXONOMY TAXY
LEFT OUTER JOIN CONTENT TCT ON TCT.IDCONTENT = TAXY.IDCONTENT
CONNECT BY TAXY.IDCATEGORY = PRIOR TAXY.IDPARENTCATEGORY

我也试过了

SELECT 
  SYS_CONNECT_BY_PATH(TAXY.CATEGORYNAME, ' \ ') AS BREADCRUMBSPATH
  , TAXY.IDCATEGORY
  , TAXY.IDPARENTCATEGORY
  , TAXY.IDCONTENT
  , TCT.CONTENTNAME 
  , TAXY.CATEGORYNAME
  , LEVEL AS LVL
FROM TAXONOMY TAXY
LEFT OUTER JOIN CONTENT TCT ON TCT.IDCONTENT = TAXY.IDCONTENT
START WITH TAXY.IDPARENTCATEGORY IS NULL CONNECT BY TAXY.IDPARENTCATEGORY = PRIOR TAXY.IDCATEGORY

但我得到相同的结果（只有 IDCONTENT 不是 NULL 的值）

最奇怪的是查询昨天在开发数据库上按预期工作，现在却不是。所以我创建了一个 fiddle 来检查我是否可以重现以前的结果并且它工作正常...... http://sqlfiddle.com/#!4/ecb9d/1 http://sqlfiddle.com/#!4/ecb9d/3

是什么导致了这种行为变化？

Answer 1

我仍然不知道发生了什么（仍然没有用）但是这个解决方案在这两种情况下似乎都工作得很好：

SELECT IDBRANCH, ENDNODEIDCONTENT, IDCATEGORY, IDPARENTCATEGORY, TAXYJ.IDCONTENT, TCT.CONTENTNAME AS ENDNODECONTENTNAME, CATEGORYNAME, LVL
FROM (
  SELECT CONNECT_BY_ROOT TAXY.IDCATEGORY AS IDBRANCH
  , CONNECT_BY_ROOT TAXY.IDCONTENT AS ENDNODEIDCONTENT
  , TAXY.IDCATEGORY
  , TAXY.IDPARENTCATEGORY
  , TAXY.IDCONTENT
  , TAXY.CATEGORYNAME
  , LEVEL AS LVL
FROM TAXONOMY TAXY
CONNECT BY TAXY.IDCATEGORY = PRIOR TAXY.IDPARENTCATEGORY
) TAXYJ 
LEFT OUTER JOIN CONTENT TCT ON TCT.IDCONTENT = TAXYJ.ENDNODEIDCONTENT

http://sqlfiddle.com/#!4/ecb9d/4

与 CONNECT_BY_ROOT 的左外连接

LEFT OUTER JOIN with CONNECT_BY_ROOT

sql

oracle10g

connect-by

hierarchical-query