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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6103) Improve documentation of ROW_NUMBER function
Date Fri, 19 Apr 2013 03:21:16 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13635987#comment-13635987
] 

Dag H. Wanvik commented on DERBY-6103:
--------------------------------------

Thanks, Kim! The syntax looks correct now. We can probably defer factoring out WindowSpecification
to a separate topic since its currently trivial. Just two more nits and we should be done:

ROW_NUMBER function topic:

"You can specify a WindowName in order to use a WINDOW clause in a SelectExpression. "

This sentence, while correct, sounds a bit rationale inverted: One would use a WindowName
iff one chose to use an explicit WindowClause in a SelectExpression rather than using an implicit
(inlined) window specification. Currently, this possibility doesn't give you much, admittedly,
but it's legal SQL syntax.

Window Clause topic:

"Currently, the only valid WindowSpecification is a set of empty parentheses (())."

Correct, but we should add that this means that the effective window is the entire result
set - as you do say in the ROW_NUMBER function topic.


                
> Improve documentation of ROW_NUMBER function
> --------------------------------------------
>
>                 Key: DERBY-6103
>                 URL: https://issues.apache.org/jira/browse/DERBY-6103
>             Project: Derby
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 10.10.1.1
>            Reporter: Dag H. Wanvik
>            Assignee: Kim Haase
>            Priority: Minor
>         Attachments: DERBY-6103-2.diff, DERBY-6103-2.stat, DERBY-6103-2.zip, DERBY-6103-3.diff,
DERBY-6103-3.zip, DERBY-6103.diff, DERBY-6103.stat, DERBY-6103.zip
>
>
> The current documentation doesn't mention that we allow the window definition to be explicit.
> The restriction on WHERE clause no longer applies, nor does the sentence about ORDER
BY not being allowed in subqueries. Cf. rreffuncrownumber.dita. Also, the documentation mentions
that we don't support LIMIT, but not that we now support the FETCH/OFFSET clause, which is
often a better option than ROW_NUMBER.

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