The Relational Model and Normalization - Database Processing: Fundamentals, Design, and Implementation - page 119

ORDER_ITEM

SKU_DATA

SKU_ITEM

Figure 3-1
How Many tables?

You can design the new database to store this data as two separate
tables, or you can join the tables together and design the database with just
one table. Each alternative has advantages and disadvantages. When you
make the decision to use one design, you obtain certain advantages at the
expense of certain costs. The purpose of this chapter is to help you under-
stand those advantages and costs.
Such questions do not seem difficult, and you may be wondering why
we need two chapters to answer them. In truth, even a single table can
have surprising complexity. Consider, for example, the table in Figure 3-2,

PRODUCT_BUYER

Figure 3-2
PrODUCt_BUYEr—a Very
Strange table