Question abount Unique Keys

Hi!

I have a question about unique keys:

When I issue the statement
CREATE UNIQUE INDEX UK_TBDOCUMENT ON TBDOCUMENT(DOCUMENTID) Oracle creates a unique index (as in user_indexes) but no unique constraint
(as in user_constraints)

When I issue that statement in a create table statement create table....

    CONSTRAINT UK_TBDOCUMENT
        UNIQUE (DOCUMENTID)
Oracle creates a unique constraint plus an index.

Why is Oracle doing this? Could somebody please shed some light on this?

This is 8.1.6 on Win2k.

Thanks,
Helmut

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Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Helmut Daiminger
  INET: hdaiminger_at_vivonet.com

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