DATABASE SYSTEMS COURSEWORK Essay Example | Topics and Well Written Essays - 1500 words

DATABASE SYSTEMS COURSEWORK - Essay ExampleThe alliance type has_ elaborate binds the learner, invoice and room entities. As the invoice entity has details of both the student and the room and also its own properties needs to be linked with all the three to depict the relation.d. The blood reside links student and hall entities. As students reside in the hall in a particular room.This conceptual model depicts all the entities and their relations it gives the overall limning and understanding of the clay to a novice. This can also be called a uniform model as it does not chance upon into consideration any DBMS in mind and shows the logical association of the system. abutting we are constructing the logical system which has the cardinality ratios. A cardinality ratio of a binary relation is the maximum itemise of instances an entity can record in a given relationship type. Logical modelThe logical model is as followsThe going away here is that the entities here are associat ed with their relationships with the cardinality ratios respectively.The cardinality ratios are derived as follows1. Between student and staff (MN).a. 1 student is responsible to 1 staffb. Many (M) students are responsible to 1 staff.c. 1 staff takes certificate of indebtedness of 1 studentd. Many (M) staff takes responsibility of many students.2. Between student and hall (N1).a. 1 student resides in 1 hall.b. Many (M) students reside in 1 hall.c. 1 hall accommodates 1 studentd. Many (M) halls do not accommodate 1 student.3. Between student, hall and invoice (111).a. 1 invoice has details of 1 student and his hall.b. 1 invoice does not have details of more than 1 student and their halls.c. Many invoices do not have details of many students and various halls.4. Between student and room (11).a. 1 student... This conceptual model depicts all the entities and their relations it gives the overall picture and understanding of the system to a novice. This can also be called a logical mod el as it does not take into consideration any DBMS in mind and shows the logical association of the system.Next we are constructing the logical system which has the cardinality ratios. A cardinality ratio of a binary relation is the maximum number of instances an entity can participate in a given relationship type.Special note The refer named lease to the relationship named rent has been shifted to the rent table as the cardinality ratio is 11 so any attribute of the relationship type must be shifted on either side.The arrows show the functional dependencies. The single arrow with no point head determines all the attributes of the entire entity. In the table Responsible_For which was previously a relationship surrounded by student and staff had a cardinality ratio of MN. The relationship type will form a separate table with the same name having the primary keys of both the aligned tables.a. Only the table Room has an attribute called Room Type which can have both single and double rooms in a particular hall.