Chapter 7. Multiple Column Data Elements
THE CONCEPT OF A data element being atomic or scalar is usually taken to mean that it is represented with a single column in a table. This is not always true. A data element is atomic when it cannot be decomposed into independent, meaningful parts. Doing so would result in attribute splitting, a design flaw that we discussed in Section 1.1.11.
Consider an (x, y) coordinate system. A single x or y value identifies a line of points, while the pair has to be taken together to give you a location on the plane. It would be inconvenient to put both coordinates into one column, so we model them in two columns.
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