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From Kathey Marsden <kmarsdende...@sbcglobal.net>
Subject Re: regarding unique keys in derby..
Date Fri, 20 Jul 2007 22:54:24 GMT
Ravinder Reddy wrote:
>
>     hi all,
>         w.r.t DERBY-2945(convert lang/primarykey.sql to junit)
> I have a small doubt.
>
> There is a test for verifying a unique key can not contain nulls.
>
> 1)-- verify that a unique key can not contain nulls
>   create table pos1 (c1 int not null unique, c2 int);
>   insert into pos1 (c1) values(null);
>   insert into pos1 (c1) values(null);
>   select * from pos1;
>   drop table pos1;
>     And It tests that null values are not allowed in c1.
>     Irrespective of uniqueness , c1 can't contain null values as it is 
> defined as not null.It seems that the test is wrong.
The test seems reasonable enough, but I guess it is really testing that 
not null works #:)
We could have a test like the one below if we don't have one already.
ij> create table pos1 (c1 int unique, c2 int);
ERROR 42831: 'C1' cannot be a column of a primary key or unique key 
because it can contain null values.
>
> 2) I am shocked to know that Derby doesn't allow a unique key column 
> to contain NULL values.can some somebody justify it.?
>
You are easily shocked #:)


Kathey



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