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https://issues.apache.org/jira/browse/DERBY-5557?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13251531#comment-13251531
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Kim Haase commented on DERBY-5557:
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Thanks for the advice, Dag and Knut!
I think it would be a good idea to provide a second patch instead of committing
this one. The additional changes would do the following:
1) call NULLIF a function rather than an expression
2) move the CASE expression topic under "SQL expressions" (not sure where;
possibly after "Boolean expressions"?)
3) modify the "SQL expressions" topic
(http://db.apache.org/derby/docs/dev/ref/rrefsqlj19433.html) to add a mention
of CASE expressions to the "Conditional expression" row of the first table. As
far as I can tell, conditional expressions include only the CASE expression and
the NULLIF and COALESCE functions, so perhaps all three should be mentioned?
I'll work on this -- if you have more suggestions, or answers to my questions,
please go ahead!
> NULLIF topic in reference manual should explain NULLIF
> ------------------------------------------------------
>
> Key: DERBY-5557
> URL: https://issues.apache.org/jira/browse/DERBY-5557
> Project: Derby
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 10.8.2.2
> Reporter: Knut Anders Hatlen
> Assignee: Kim Haase
> Attachments: DERBY-5557.diff, rrefcasenullif.html
>
>
> The section describing NULLIF in the reference manual is a bit cryptic.
> http://db.apache.org/derby/docs/10.8/ref/rrefcasenullif.html
> It says that NULLIF is used for conditional expressions, and that it is
> similar to CASE, but it doesn't say in plain words how it works. It would be
> good if it could mention that NULLIF returns NULL if the two arguments are
> equal, and that it returns the first argument if they are not equal.
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