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Posted to derby-dev@db.apache.org by "Dag H. Wanvik (JIRA)" <ji...@apache.org> on 2012/10/19 17:38:11 UTC
[jira] [Comment Edited] (DERBY-5957) 0 returned instead of NULL
with correlated scalar subquery in select list
[ https://issues.apache.org/jira/browse/DERBY-5957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13480077#comment-13480077 ]
Dag H. Wanvik edited comment on DERBY-5957 at 10/19/12 3:37 PM:
----------------------------------------------------------------
Closing as invalid: pilot error; the "0" came from ResultSet#getInt; checking with ResultSet#wasNull shows its really NULL. Safer to use getString :-)
was (Author: dagw):
Closing as invalid: pilot error; the "0" came from ResultSet#getInt; checking with ResultSet#wasNull shows its really NULL. Safer to user getString :-)
> 0 returned instead of NULL with correlated scalar subquery in select list
> -------------------------------------------------------------------------
>
> Key: DERBY-5957
> URL: https://issues.apache.org/jira/browse/DERBY-5957
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.9.1.0
> Reporter: Dag H. Wanvik
>
> In DERBY-5954 we saw an example query that returned 0 instead of NULL if a correlated scalar subquery in a select list didn't find a row, and another column in the select list has a values, i.e.:
> s.executeUpdate("create table derby5954( a int )");
> s.executeUpdate("insert into derby5954 values 1,2,3,4,5,6,7");
> ResultSet rs = s.executeQuery(
> "SELECT a_t1, (" +
> " SELECT a_t2 FROM (" +
> " SELECT a as a_t2 FROM derby5954) " +
> " as T2" +
> " where T2.a_t2 = T1.a_t1 + 1 ) " +
> " as a_outer" +
> " FROM (SELECT a as a_t1 from derby5954) as T1");
> gives
> 1 2
> 2 3
> 3 4
> 4 5
> 5 6
> 6 7
> 7 0
> where the last row's second column should be NULL, not "0"., since in the predicate T2.a_t2 = T1.a_t1 + 1
> there will be no T2.a_t2 which matches 7 (T1.a_t1's last row) + 1.
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