[DERBY-2459] Ordering on a CASE-expression casues a NullPointerException when using a UNION

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.1.3.1, 10.1.3.2, 10.2.1.6, 10.2.2.0, 10.2.2.1, 10.3.1.4
• Fix Version/s: 10.3.1.4
• Component/s: SQL
• Environment: Java 1.5.0_06-b05 on Linux Ubuntu 5.10. Derby version 10.2.2
• Assignee: Bryan Pendleton
• Reporter: Lars Gråmark
• Created: 16/Mar/07 10:39
• Updated: 21/Jan/11 17:49
• Resolved: 05/Jun/07 16:05

Description

When an order by clause involves a CASE-expression as seen below, a NullPointerException is thrown. The error only occurs when two select statements are combined in a union (or union all).

select t1.id, CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END
from A1 t1
left outer join B1 t2 ON t2.id = t1.ref

union all

select t1.id, CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END
from A2 t1
left outer join B2 t2 ON t2.id = t1.ref

order by CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END

--Use the following statement to reproduce the problem:

create table A1
(
id char(1)
,value int
,ref char(1)
);

create table A2
(
id char(1)
,value int
,ref char(1)
);

create table B1
(
id char(1)
,value int
);

create table B2
(
id char(1)
,value int
);

insert into A1 (id, value, ref) values ('a', 12, 'e');
insert into A1 (id, value, ref) values ('b', 1, null);
insert into A2 (id, value, ref) values ('c', 3, 'g');
insert into A2 (id, value, ref) values ('d', 8, null);

insert into B1 (id, value) values ('e', 4);
insert into B1 (id, value) values ('f', 2);
insert into B2 (id, value) values ('g', 5);

Issue Links

• is related to: DERBY-1861 Column ordering ASSERT when combining column references and expressions in same ORDER BY