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From Rick Hillegas <Richard.Hille...@Sun.COM>
Subject Re: ENUM
Date Fri, 08 Sep 2006 14:10:49 GMT
As a further refinement on this excellent approach, you can encapsulate 
the validator in a function. Something like this:

CREATE TABLE standard (
 sizes VARCHAR(32) CONSTRAINT sizes_ck CHECK ( sizeIsLegal( sizes ) )
);

For more information on how to wire Java methods into your DDL and 
queries, please see the Derby Reference Manual section on "CREATE FUNCTION".

Hope this helps,
-Rick

Dan Scott wrote:

> On the SET datatype: Even the MySQL docs include a section upfront
> called "Why you shouldn't use SET"
> (http://dev.mysql.com/tech-resources/articles/mysql-set-datatype.html).
> It's not an atomic datatype. Bad.
>
> On ENUM: The SQL standard way of doing the equivalent of ENUM, and
> therefore the Derby way, is to define a check constraint on the
> column.
>
> For example, in MySQL you might do something like:
>
> CREATE TABLE nonstandard (
>  sizes ENUM('small', 'medium', 'large')
> );
>
> Implementing this as a check constraint in Derby, on the other hand,
> would look something like:
>
> CREATE TABLE standard (
>  sizes VARCHAR(32) CONSTRAINT sizes_ck CHECK (sizes IN ('small',
> 'medium', 'large'))
> );
>
> Pretty simple.
>
> Dan
>
> On 08/09/06, Chee Cheng <chee.k.cheng@gmail.com> wrote:
>
>> Hi,
>>
>> Does Derby offer enumeration type like ENUM and SET?  If not, what's the
>> best way to restrict a column to certain pre-defined value?
>>
>> Thank you.
>>
>>


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