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 <[EMAIL PROTECTED]> 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.
