Business Rules and Data Models Essay

A database is a structure that contains teaching about many another(prenominal) different categories of information and about the relationships between those categories (Pratt & Adamsk 2010). Database object lenss ar entities that exist at heart a database to support operations such as storing, retrieving and manipulating data. Organizations use giant amounts of data and database management system to store and transform data into information to support making decisions.A database management system consists of the following trinity elements 1. The physical database the collection of files that contain the data. 2. The database engine the software that makes it viable to admission fee and modify the contents of the database. 3. The database scheme the specifications of the logical structure of the data stored in the database. As we know, database is structured collection of data computer based databases are usu tout ensembley organized into champion or more bows. A table sto res data in a format similar to a published table and consists of a series of rows and columns. In a database model, each object that we want to track in the database is known as entitiy. For example, in a college database there might be some(prenominal) entities which is known as garment of similar objects. Some of the entities in college database are1. Student2. Professor3. careers4. EmployeesAttributes describes one aspect of an entity type. Entity type is described by intend of pass judgments. An entity is a real-world tip or concept that exists on its own (Shiflet, 2002). The set of all possible values for an entity is the entity type. Each entity has attributes, or particular properties that describe the entity. For example educatee Indra Paudel has properties of hisown studentID, StudentName and StudentGrade. Figure 1 E-R Diagram notation for an attribute reality ( StudentGrade ) of an entity type (Student).Lets have a close grammatical construction of each entity a nd their attributes. Figure 1.1 the attributes of Student entity.Figure 1.3 the attributes of physique entity.An entity is a differentiable object in the enterprise. An entity has attributes that describe the properties of the entity. For example, a course is an object in the student information system. The course number, title, credits, and prerequisites are the attributes for the course. All the courses have aforesaid(prenominal) type of attributes. A collection of entities of the same attributes is called an entity set. Since each entity is distinct, no two entities whoremonger have the same values on the attributes. Each entity phratry has an attribute or a set of attributes that can be utilize to uniquely identify the entities. In case there are several(prenominal) keys in the entity class, we can designate one as the primary election key. For example, we can designate the course title to be the key, assume that every course has a different title. A composite attribute is an attribute that is cool of two or more sub-attributes. For example, the Student entity class has the address attribute that consists of street, city, state, and zipcode. A multivalued attribute is an attribute that may consist of a set of values. For example, the Course entity class has the prerequisites attribute. A course may have several prerequisites. Therefore, the prerequisites attribute is a multivalued attribute.A derived attribute is an attribute that can be derived or calculated from the database. A derived attribute should not be stored in the database. For example, we may add an attribute named numOfPrerequisites to the Course entity class. This attribute can be calculated from the prerequisites attribute. Example of business ruleDepartmentoffersCourseCourseGenerates-ClassProfessorTeachesClassA conceptual data model identifies the highest train relationships between the different entities, whereas physical data models represent how the model go away be built in t he database. A physical database model shows all table structure including column name, column data type, column constraints, primary key, foreign key, and relationships between tables.ReferencesPratt, P.J, & Adamski J.J, (2011). Concepts of Database Management. Ohio, OH CENGAGE Learning. Shiflet, A.b, (2002). Entity Relationship-Model. Retrieved from http//wofford-ecs.org/dataandvisualization/ermodel/material.htm