In mathematical terms, the difference between attribute and value-set is simply the differnce between the viable and the component within the variable. For instance, the attribute of a student can be his name. The letters of his name (the character bits) are in the set. Any combination of this characters string is in the domain / set, but actually the person / attribute himself cannot have all combinations of this domain for his name.
What is the difference between specialization and generalization? Why do we not display this difference in schema diagrams? Explain
Specialization refers to defining a set of subclasses of an entity type. The entity type itself is called the super class of the specialization. Each of these subclasses contains some particular characteristics of the superclass that singles them out. For example, the superclass 'Employee' may contain the set of subclasses {Secretary,...
Specializations may also addend characteristics so, for instance, to the above, we can add {Salaried-Employee, Hourly_Employee} which distinguished between the rate of pay of employees. Specialization allows us to define and particularize subclasses. Generalization, on the toehr hand, is the reverse process where differences are suppressed and all are lumped into a group. Schema diagrams only display some aspects of a schema, such as data items, certain types of constrains, and the names of record types therefore, differences between specialization and generalization cannot be included in schema diagrams.
What is the importance of requirements collection and analysis? What happens if this step is not carried out properly? Explain..
Interaction with potential users and user groups collects detailed requirements and analysis of these requirements. The importance of this
