Netezza不支持递归公用表表达式,否则这将是更优雅和可扩展的解决方案。我发现最好的解决方法是使用左外连接到同一个表。
创建测试表。我们使用-1来表示根节点。
CREATE TABLE t1 AS
SELECT 52 AS Org_key, 26 AS Par_Org_key
UNION
SELECT 23 AS Org_key, 89 AS Par_Org_key
UNION
SELECT 26 AS Org_key, 14 AS Par_Org_key
UNION
SELECT 14 AS Org_key, 8 AS Par_Org_key
UNION
SELECT 8 AS Org_key, -1 AS Par_Org_key;
这将返回8 | 14 | 26 | 52
SELECT NVL(a.Org_key,'0') || '|' || NVL(b.Org_key,'0') || '|' || NVL(c.Org_key,'0') || '|' || NVL(d.Org_key,'0')
FROM t1 a
LEFT OUTER JOIN t1 b ON a.Org_key = b.Par_Org_key
LEFT OUTER JOIN t1 c ON b.Org_key = c.Par_Org_key
LEFT OUTER JOIN t1 d ON c.Org_key = d.Par_Org_key
LEFT OUTER JOIN t1 e ON d.Org_key = e.Par_Org_key
WHERE a.Par_Org_key = -1;
如果你想添加更多的左外连接,以支持一个未知的数量水平,这可以帮助处理导致
的NULL
SELECT NVL(CAST(a.Org_key AS VARCHAR(10)),'') || '|' || NVL(CAST(b.Org_key AS VARCHAR(10)),'') || '|' || NVL(CAST(c.Org_key AS VARCHAR(10)),'') || '|' || NVL(CAST(d.Org_key AS VARCHAR(10)),'')
Netezza在这里是相当晦涩的话题。在http://dba.stackexchange.com上问你可能会更好 – mvp