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Posted to derby-dev@db.apache.org by "Kim Haase (Updated) (JIRA)" <ji...@apache.org> on 2012/04/10 17:05:16 UTC

[jira] [Updated] (DERBY-5557) NULLIF topic in reference manual should explain NULLIF

     [ https://issues.apache.org/jira/browse/DERBY-5557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kim Haase updated DERBY-5557:
-----------------------------

    Attachment: DERBY-5557.diff
                rrefcasenullif.html

Thanks for noticing this problem, Knut. I'm attaching DERBY-5557.diff and rrefcasenullif.html, with your suggested modification to the NULLIF topic.

Not to open a can of worms here, but I think that in SQL, NULLIF really is a function rather than an expression. Should I retitle it?

CASE is an expression, though.

Neither CASE nor NULLIF is listed in either the "Standard built-in functions" or the "SQL expressions" topic. Is this correct?


                
> 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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