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Posted to issues@calcite.apache.org by "duan xiong (Jira)" <ji...@apache.org> on 2021/06/29 16:50:00 UTC

[jira] [Commented] (CALCITE-4486) UNIQUE predicate

    [ https://issues.apache.org/jira/browse/CALCITE-4486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17371525#comment-17371525 ] 

duan xiong commented on CALCITE-4486:
-------------------------------------

Hi. [~julianhyde] Do you have more time to work on this issue? Can I do it?

> UNIQUE predicate
> ----------------
>
>                 Key: CALCITE-4486
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4486
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Priority: Major
>
> Implement the UNIQUE predicate, as specified by the SQL standard.
> Example:
> {code:java}
> UNIQUE (SELECT publishedIn FROM Book
>             WHERE authorId = 3)
> NOT UNIQUE (SELECT publishedIn FROM BOOK
>             WHERE authorId = 3)
> {code}
> {{UNIQUE}} returns {{FALSE}} if the query returns two or more rows that do not include NULL values and are equal. Like {{EXISTS}}, it never returns {{UNKNOWN}}.
> More details at [JOOQ|https://www.jooq.org/doc/3.0/manual/sql-building/conditional-expressions/unique-predicate/].



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