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https://issues.apache.org/jira/browse/DERBY-6363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13783807#comment-13783807
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Knut Anders Hatlen commented on DERBY-6363:
-------------------------------------------
Can also be reproduced without the CASE expression:
{noformat}
ij> select a, b, (( b = 'a' or b = 'b' ) and a < 4), (a < 4 and ( b = 'a' or b
= 'b' )) from t;
A |B |3 |4
----------------------------
1 |a |true |true
2 |b |false|true
3 |a |true |true
4 |b |false|false
5 |a |false|false
6 |b |false|false
6 rows selected
{noformat}
Row 2 column 3 should have been true rather than false.
> Incorrect evaluation of logical expressions in CASE
> ---------------------------------------------------
>
> Key: DERBY-6363
> URL: https://issues.apache.org/jira/browse/DERBY-6363
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.4.1.3, 10.8.3.0, 10.10.1.1
> Reporter: Grzegorz Żur
>
> Logical expressions with AND and OR operators inside WHEN inside CASE
> expression nested in SELECT part of statement are wrongly evaluated.
> Evaluation results depends on position of OR subexpression. If OR is placed
> on left side of AND it is evaluated incorrectly.
> Following code shows the error.
> create table t ( a int, b char );
> insert into t values (1, 'a');
> insert into t values (2, 'b');
> insert into t values (3, 'a');
> insert into t values (4, 'b');
> insert into t values (5, 'a');
> insert into t values (6, 'b');
> select
> a,
> b,
> case
> when (( b = 'a' or b = 'b' ) and a < 4) then 'x'
> else '-'
> end,
> case
> when (a < 4 and ( b = 'a' or b = 'b' )) then 'y'
> else '-'
> end
> from t;
> Actual result:
> 1 a x y
> 2 b - y
> 3 a x y
> 4 b - -
> 5 a - -
> 6 b - -
> Expected result
> 1 a x y
> 2 b x y
> 3 a x y
> 4 b - -
> 5 a - -
> 6 b - -
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