oracle SQL Select 中的序列
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Sequence within SQL Select
提问by fras
I'm having a bit of a problem with using my sequence within a SELECTstatement.
在SELECT语句中使用我的序列时遇到了一些问题。
SELECT
c.cust_name,
c.site,
customer_id_seq.nextval
FROM
customer c
WHERE
c.customer_id IS NULL
ORDER BY
c.site_code ASC
;
Is giving me an error:
给我一个错误：
- 00000 - "sequence number not allowed here" *Cause: The specified sequence number (CURRVAL or NEXTVAL) is inappropriate here in the statement. *Action: Remove the sequence number.
- 00000 - “此处不允许使用序列号” *原因：在语句中指定的序列号（CURRVAL 或 NEXTVAL）在此处不合适。*操作：删除序列号。
It's probably something obvious I'm doing wrong so hopefully this will be an easy answer.
很明显我做错了，所以希望这将是一个简单的答案。
回答by Quassnoi
You cannot use sequences in queries with ORDER BY.
您不能在带有 的查询中使用序列ORDER BY。
Remove the ORDER BYor put in into a subquery:
删除ORDER BY或放入子查询：
SELECT q.*, customer_id_seq.nextval
FROM (
SELECT c.cust_name,
c.site
FROM customer c
WHERE c.customer_id IS NULL
ORDER BY
c.site_code ASC
) q
回答by KM.
for IBM Imformix
In a SELECT statement, you cannot specify NEXTVAL or CURRVAL in the following contexts:
在 SELECT 语句中，您不能在以下上下文中指定 NEXTVAL 或 CURRVAL：
- In the projection list when the DISTINCT keyword is used
- In the WHERE, GROUP BY, or ORDER BY clauses
- In a subquery
- When the UNION operator combines SELECT statements
- 在使用 DISTINCT 关键字时的投影列表中
- 在 WHERE、GROUP BY 或 ORDER BY 子句中
- 在子查询中
- 当 UNION 运算符组合 SELECT 语句时
回答by KM.
Why don't you use rownum instead of fetching values from sequence?
为什么不使用 rownum 而不是从序列中获取值？
