Oracle check constraint bug ?

Question

Hi,
This is an 'interesting' bug:
create table mytable (
id number,
status number,
constraint mytable_pk primary key (id)
insert into mytable (id, status) values (1, 0);
insert into mytable (id, status) values (2, -1);
On XE (10.2.0.1) and 10.2.0.4:
Following command gives the expected ORA-02293 error (using string values instead of numbers): alter table mytable add constraint mytable_status_chk check (status in ('0', '1'));
BUT no error with the following command: alter table mytable add constraint mytable_status_chk check (status in ('-1', '0', '1'));
On XE:
The query select * from mytable where status=0 returns no records until the constraint is dropped again !
Best regards,
Serge
Edited by: sergeko on Nov 19, 2010 11:19 AM
Edited by: sergeko on Nov 19, 2010 11:21 AM

Answer 1

I don't have access to any 10.x or XE currently and cannot reproduce on EE 9.2.0.9 or 11.1.0.6.
It's possible that you're running into an optimizer issue with the constraint.
This might be visible if you run an explain plan on the statement, get the execution plan via dbms_xplan.display and check the predicates section both with and without the constraint.
I take it that you don't get the problem if you use a check constraint with numbers not strings.
I wonder also whether it makes a difference if you declare status as not null.
Edited by: DomBrooks on Nov 19, 2010 10:44 AM