Addison Wesley Longman Inc. We need to start with an explanation of business rules and their possibilities. He goes on to say, The factor underlying both of these problems is the amount of code it takes to build a system . If code is the problem, the only possible answer is to eliminate the coding by building systems directly from their specifications. Just to be definite in our example shown in figure 1, assume the database is an SQL database specifically and the boxes represent SQL tables. And those existence dependencies are business rules.
Foreign keys correspond to an important special case of business rules in general.
That form will include fields for the customer number, the order number, the part number, and the quantity ordered. A. It checks the customer's credit limit. B. It computes the order total. It determines whether the part needs to be reordered. Here, A, B, and C are business requirements that must be met in order to carry out the overall business function.