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Required property of Primary Key fields
On 7 Sep, 14:13, "Ken Snell \(MVP\)"
wrote: While usnig another table to be the junction between the backordered items table and the purchase order items table is certainly feasible, it seemed to be an unnecessary structure for my design. Design is in part art IMO. I think my design is better in principle because I don't consider 'backorder item ID' (or whatever) to be an attribute of a 'purchase order item' (surely 'backorder item ID' comes into existence before the purchase order item' therefore how can it be its attribute?) and better in practice because it doesn't involve redundantly storing a bunch of NULLs to indicate that no relationship exists (I can generate those NULLs on demand with an outer join). Is better not good enough? Must it be proved "necessary" g? Jamie. -- |
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