Most of the time a primary key should be generated and not be a combination of other fields. I believe this practice solves far more problems than it causes.

>This post is dealing with my earlier post.
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>I have a document with a number, revision, and submittal number. This is one table.
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>A second table holds document items belonging to the documents in the first table.
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>If I want a one table to many table relation, would it be better to have a field that holds a unique index of the particular document, than to index on the doc, rev, sub no comination.