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From "Laszlo Bodor (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-16505) Support "unknown" boolean truth value
Date Thu, 31 May 2018 08:10:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-16505?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Laszlo Bodor updated HIVE-16505:
--------------------------------
    Attachment: HIVE-16505.01.patch

> Support "unknown" boolean truth value
> -------------------------------------
>
>                 Key: HIVE-16505
>                 URL: https://issues.apache.org/jira/browse/HIVE-16505
>             Project: Hive
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Zoltan Haindrich
>            Assignee: Laszlo Bodor
>            Priority: Major
>         Attachments: HIVE-16505.01.patch
>
>
> according to the standard, boolean truth value might be: {{TRUE|FALSE|UNKNOWN}}.
> similar queries to the following should be supported:
> {code:java}
> select 1 where null is unknown;
> select 1 where (select cast(null as boolean) ) is unknown;
> {code}
> "unknown" behaves similarily to null. {{(null=null) is null}}
>  
> "All boolean values and SQL truth values are comparable and all are assignable to a site
of type boolean. The value True is greater than the value False, and any comparison involving
the null value or an Unknown truth value will return an Unknown result. The values True and
False may be assigned to any site having a boolean data type; assignment of Unknown, or the
null value, is subject to the nullability characteristic of the target."
>  
> *Truth table for the AND boolean operator*
> AND True False Unknown
> True True False Unknown
> False False False False
> Unknown Unknown False Unknown
> *Truth table for the OR boolean operator*
> OR True False Unknown
> True True True True
> False True False Unknown
> Unknown True Unknown Unknown
> *Truth table for the IS boolean operator*
> IS TRUE FALSE UNKNOWN
> True True False False
> False False True False
> Unknown False False True
>  



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