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Michael Sokolov scripsit: > let's map "xml root element name" to "table" and "document" to "row" Sounds right. It's "column" that's the hard idea. Which of the objects in a document count as columns? Normal column names are just identifiers, although it's possible to use arbitrary characters in a column name if you wrap it in single quotes, so that would be an escape for getting XPath expressions (though they would have to be single-valued ones). But the expectation is that there would be a natural mapping of ordinary identifiers, and what would that be? Should we map the column identifier foo to the XPath /foo[1], or perhaps //foo[1]? > This might be enough for selects, but I guess for inserts you'd have > to define column mappings. Not just for inserts, but for selects as well, as shown above. For inserts you also have to define an *order* of columns and keep it in the database somewhere, so that you can interpret "insert into foo values(1, 2, 3)" and know what column names are implied. > These would probably have to be drawn from some subset of all xpath > expressions like forward steps only, no function calls, something like > that - I think MarkLogic searchable xpath expression is something like > this). You would have to introduce a new kind of schema for defining > these mappings. That makes sense for the escaped version of column names, except that as I say SQL expects a column to be single-valued, so you need an expression guaranteed to return one value. -- [W]hen I wrote it I was more than a little John Cowan febrile with foodpoisoning from an antique carrot cowan@c... that I foolishly ate out of an illjudged faith http://ccil.org/~cowan in the benignancy of vegetables. --And Rosta
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