1

我正在执行以下查询并为所有列使用别名。我用 . 因为这是一个要求。现在，我想直接在 where 子句中引用别名，如下所示：

SELECT pt.prod_desc AS"PROD_DESC",
 (
CASE
WHEN pt.prod_level='2'
THEN 'Product'
WHEN pt.prod_level='4'
THEN 'Sub-Product'
WHEN pt.prod_level='5'
THEN 'Service'
ELSE 'N/A'
 END)         AS"PROD_LEVEL",
prod_id      AS "PROD_ID",
isactive     AS "IsActive",
updt_usr_sid AS "UPDT_USR_SID",
updt_ts      AS "UPDT_TS",
(
CASE
WHEN pt.prod_level='5'
THEN parent_prod_id
ELSE NULL
  END) AS ".SUB_PROD_ID",
(
 CASE
  WHEN pt.prod_level='5'
  THEN
  (SELECT prod_desc FROM dims_prod_type A WHERE A.prod_id= pt.parent_prod_id
  )
  ELSE 'N/A'
 END ) AS ".SUB_PROD_DESC",
 (
CASE
WHEN pt.prod_level='4'
THEN parent_prod_id
WHEN pt.prod_level='5'
THEN
  (SELECT parent_prod_id
  FROM dims_prod_type A
  WHERE A.prod_id= pt.parent_prod_id
   )
 ELSE NULL
   END) AS ".PRNT_PROD_ID",
(
 CASE
 WHEN pt.prod_level='4'
THEN
   (SELECT prod_desc FROM dims_prod_type A WHERE A.prod_id=pt.parent_prod_id
   )
  WHEN pt.prod_level='5'
THEN
   (SELECT prod_desc
   FROM dims_prod_type A
  WHERE A.prod_id IN
    (SELECT B.parent_prod_id
    FROM dims_prod_type B
    WHERE b.prod_id=pt.parent_prod_id
    )
  )
 ELSE 'N/A'
 END)AS ".PRNT_PROD_DESC"
FROM dims_prod_type pt
WHERE pt.".PRNT_PROD_ID" like 'A%';

但是，当我执行此操作时，出现以下错误：

    SQL Error: ORA-00904: "PT".".PRNT_PROD_ID": invalid identifier
     00904. 00000 -  "%s: invalid identifier"

我知道 SQL 首先执行 where 子句，因此这就是错误的原因。但是我该如何解决这个问题？请问有什么建议吗？

4

3 回答 3

2

您已经知道不能在where子句中使用别名，但这仅适用于同一级别的 SQL。您可以将查询包装在外部查询中：

SELECT *
FROM (
  SELECT pt.prod_desc AS"PROD_DESC",
  ...
   END)AS ".PRNT_PROD_DESC"
  FROM dims_prod_type pt
)
WHERE ".PRNT_PROD_ID" like 'A%';

唯一的选择是case在子句中重复生成该列的整体，where这对于如此复杂的事情会令人不快。

于 2014-02-05T08:12:26.120 回答
1

Put the query in a subquery, then you can refer to the aliases in your where clause, e.g.:

SELECT * FROM (
  SELECT pt.prod_desc AS"PROD_DESC",
   ...etc...
  FROM dims_prod_type pt) pt
WHERE pt.".PRNT_PROD_ID" like 'A%';
于 2014-02-05T08:11:36.183 回答
0

将 "PT".".PRNT_PROD_ID" 替换为 "PT"."PRNT_PROD_ID" 或通过 pt.prnt_prod_id 更好地理解

于 2014-02-05T07:50:06.023 回答