4.11 Separation of Edges and Nodes 103 they are different kinds of things, they need to be in separate tables. Not only is this just good data modeling, but it has some very practical advantages. 4.11.1 Multiple Structures As an example, a shoe company had two reporting hierarchies: one for the manufacturing side of the company, which was based on the physical con- struction of the footwear, and another volatile hierarchy for the marketing department. The marketing hierarchy was based on where and to whom the shoes were sold. For example, steel-toed work boots were one category in the manufacturing reports. But at that time, there were two distinct groups of buyers of steel-toed work boots: construction workers with really big feet and teenaged girls into punk rock with really small feet. People with average-sized feet did not wear these things. For marketing, size was a vital factor, and for manufacturing, it was a few switches on a shoe-making machine. CREATE TABLE Shoes