[
https://issues.apache.org/jira/browse/DERBY-4513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12799731#action_12799731
]
Knut Anders Hatlen commented on DERBY-4513:
-------------------------------------------
Thanks for clarifying, Rick.
So both of these (presumably SQL compliant) statements will be rejected?
SELECT NEXT VALUE FOR S, NEXT VALUE FOR S FROM T -- two clauses per row
VALUES (NEXT VALUE FOR S), (NEXT VALUE FOR S) -- two clauses in the
statement, but only one per row
The VALUES case is probably more useful than the SELECT case, especially as
part of an INSERT statement. The restriction would basically prevent us from
using a sequence generator in a multi-row insert. That's probably fine in the
initial implementation, though, and anyone could scratch that itch later if
they want to.
> Forbid NEXT VALUE FOR clause in certain contexts
> ------------------------------------------------
>
> Key: DERBY-4513
> URL: https://issues.apache.org/jira/browse/DERBY-4513
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.6.0.0
> Reporter: Rick Hillegas
>
> This is part of the work needed to implement ANSI/ISO sequences. The
> functional spec attached to DERBY-712 lists various situations in which the
> NEXT VALUE FOR clause is illegal. These include:
> * CASE expression
> * WHERE clause
> * ORDER BY clause
> * AGGREGATE expression
> * WINDOW function
> * DISTINCT select list
> In addition, I propose that we make it illegal for a statement to have more
> than one NEXT VALUE FOR clause on the same sequence generator. This is a
> tighter restriction than the ANSI/ISO standard calls for. The standard
> requires that if two columns in a row are populated by NEXT VALUE FOR clauses
> on the same sequence, then the values should be the same. I don't feel
> confident that I could track down all of the cases which could give rise to
> this situation--so I propose to limit the number of NEXT VALUE FOR clauses on
> a given sequence generator to just 1.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
