Relation-Entiry Diagram Question/Problem

I am trying to describe/document a database that I have implemented, and don't quite know how to proceed

The entities are
(1) Statements
(2) Documents
(3) Document Amendment
(4) Statement Corrections

Relationships are
(1) Documents contain statements
(2) One document can amend another document,
but a document used as an amendment itself can not be amended
(3) Statement Corrections are made under the authority of a Document
Amendment
A statement correction implies a relationship between a statement of the amended document
and a statement of the amending document

I think the following is incorrect

                       ............................
            ***** .  Statements       . ******
            *         ............................           *
            *                   *                           *
            *                   *                           *
            *         ............................           *
            *         .  Documents       .           *
            *         ............................           *
            *            *                *                *
            *            *                *                *
            *         ............................           *
            *         .  Document         .           *
            *         .    Amendments   .           *
            *         ............................           *
            *                   *                           *
            *                   *                           *
            *         ............................           *
            *         .  Statement         .           *
            ***** .   Corrections     . ******
                       ............................

because it implies any statement can amend any other statement
(which is most definitely not the intent)

In the actual implementation there is a query named Statements_Of_Document

The query serves to identify the candidate statements for the amended statement and the amending statement in the Statement Correction Relationship

How do I identify the constraint on the Statement Corrections relationship.

I am inclined to treat Statements_Of_Document as an entity, even though it is redundant. Received on Sun Mar 11 2001 - 17:35:49 CET