[jira] [Commented] (DERBY-6408) EXISTS returns NULL instead of FALSE

["Mike Matrigali (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-6408?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13905848#comment-13905848 ] 

Mike Matrigali commented on DERBY-6408:
---------------------------------------

10.2 get following syntax error:
ij version 10.2
CONNECTION0* -  jdbc:derby:wombat
* = current connection
ij> create table t(x int);
0 rows inserted/updated/deleted
ij> values exists(select * from t);
ERROR 42X80: VALUES clause must contain at least one element. Empty elements are not allowed.


> EXISTS returns NULL instead of FALSE
> ------------------------------------
>
>                 Key: DERBY-6408
>                 URL: https://issues.apache.org/jira/browse/DERBY-6408
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.10.1.1
>            Reporter: Knut Anders Hatlen
>
> The reference manual topic on Boolean expressions - http://db.apache.org/derby/docs/10.10/ref/rrefsqlj23075.html - says that EXISTS should return FALSE if the subquery returns no rows. In reality, it returns NULL:
> ij> create table t(x int);
> 0 rows inserted/updated/deleted
> ij> values exists(select * from t);
> 1    
> -----
> NULL 
> 1 row selected
> SQL:2011, part 2, 8.10 <exists predicate> also says that FALSE is the correct result if the cardinality is 0.



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