'Business Rules and Data Models Essay\r'

'A infobase is a construction that confines discipline about many divers(prenominal) categories of culture and about the relationships between those categories (Pratt & vitamin A; Adamsk 2010). Database objects are entities that make it within a entropybase to support operations such as storing, retrieving and manipulating data. Organizations use large amounts of data and database direction placement to store and transform data into information to support making decisions.\r\nA database management system consists of the following three elements: 1. The physical database: the collection of files that contain the data. 2. The database engine: the software that makes it possible to access and qualify 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 form into maven or more circuit cards . A table stores data in a format analogous to a published table and consists of a series of rows and columns. In a database assume, each object that we motivation to track in the database is known as entitiy. For typesetters case, in a college database there might be several(prenominal) entities which is known as narrow of similar objects. any(prenominal) of the entities in college database are:\r\n1. Student\r\n2. professor\r\n3. tracks\r\n4. Employees\r\nAttributes diagnoses one aspect of an entity type. Entity type is described by set of delegates. An entity is a real-world item or concept that exists on its own (Shiflet, 2002). The set of all possible determine for an entity is the entity type. Each entity has portions, or particular properties that describe the entity. For example savant Indra Paudel has properties of his\r\nown studentID, StudentName and StudentGrade. Figure 1 E-R plat notation for an associate domain ( StudentGrade ) of an entity type (Student ).\r\n allow’s brook a close wait on of each entity and their attributes. Figure 1.1 the attributes of Student entity.\r\nFigure 1.3 the attributes of personal line of credit entity.\r\nAn entity is a distinguishable 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 pack similar type of attributes. A collection of entities of the same attributes is called an entity set. Since each entity is distinct, no two entities buns dumbfound the same values on the attributes. Each entity trend has an attribute or a set of attributes that can be used to uniquely identify the entities. In case there are several keys in the entity score, we can designate one as the old 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 smooth 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.\r\nA derived attribute is an attribute that can be derived or mensural 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 origin rule:\r\nDepartmentâ€â€offersâ€â€Course\r\nCourseâ€â€Generatesâ€â€-Class\r\nProfessorâ€â€Teachesâ€â€Class\r\nA conceptual data model identifies the highest level r elationships between the different entities, whereas physical data models represent how the model will be built in the 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.\r\nReferences\r\nPratt, 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\r\n'