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https://issues.apache.org/jira/browse/DERBY-2256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466118
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A B commented on DERBY-2256:
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Yip's most recent comment agrees with what Mike wrote on derby-dev:
http://thread.gmane.org/gmane.comp.apache.db.derby.devel/35489/focus=35559
To quote Mike: "My guess would be that [...] some problem is applying the real
qualifiers to integer comparisons, where for some reason that compare is
different for transformed query."
> Wrong Results: Use of decimal values in an IN-list with INTEGER left operand
> can lead to extra rows.
> ----------------------------------------------------------------------------------------------------
>
> Key: DERBY-2256
> URL: https://issues.apache.org/jira/browse/DERBY-2256
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.0.2.0, 10.0.2.1, 10.0.2.2, 10.1.1.0, 10.1.2.1,
> 10.1.3.1, 10.1.3.2, 10.1.4.0, 10.2.1.6, 10.2.2.0, 10.2.2.1, 10.2.3.0, 10.3.0.0
> Reporter: A B
>
> While trying out some code changes for DERBY-47 I was running a few test
> cases and happened to notice that there are a couple of cases in which Derby
> behaves incorrectly (that or my understanding of what should be happening
> here is way off).
> First and most simply: the following query should return zero rows (unless
> I'm missing something?), but it returns one:
> ij> create table t1 (i int);
> 0 rows inserted/updated/deleted
> ij> insert into t1 values 1, 2, 3, 4, 5;
> 5 rows inserted/updated/deleted
> -- Correct returns zero rows.
> ij> select * from t1 where i in (4.23);
> I
> -----------
> 0 rows selected
> -- But this one returns 1 row...
> ij> select * from t1 where i in (2.8, 4.23);
> I
> -----------
> 4
> 1 row selected
> Secondly, if the IN-list contains a non-constant value then Derby can
> incorrectly return rows that do not match the IN predicate. I think this is
> because some internal casting is happening when it shouldn't?
> ij> create table t1 (i int);
> 0 rows inserted/updated/deleted
> ij> insert into t1 values 1, 2, 3, 4, 5;
> 5 rows inserted/updated/deleted
> -- Following values clause returns "2.80", as expected.
> ij> values cast (2.8 as decimal(4, 2));
> 1
> -------
> 2.80
> 1 row selected
> -- But if we use it in an IN-list it gets cast to "2" and thus returns a
> match.
> -- We get 2 rows when we should get NONE.
> ij> select * from t1 where i in (cast (2.8 as decimal(4, 2)), 4.23);
> I
> -----------
> 2
> 4
> 2 rows selected
> I confirmed that we see these results on trunk, 10.2, 10.1, and even as far
> back as svn #201660 for 10.0. I also ran the above statements on DB2 v8 as a
> sanity check to confirm that NO results were returned there.
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