Problem Survey
- 1. Obtaining Information from a Database Management System
- 2. OverviewModels are used to
- 3. BackgroundStudent’s grades are comprised of grades for individual projects, group projects, and extra credit projects.Each grade is on a scale of 0 to 100. Student information, including grades, is stored in the school’s computer systemThe information is stored in a database system that organizes the information logically into tablesThe entries in the student table contains basic information about the student – name, address, sex, phone number, etcEntries in another table stores information about projects – for example name of the project, date assigned, date due and the gradeFor an individual project, each entry on the project table is associated with an entry on the student tableThe following diagram shows how the information is stored in the two tables
- 4. Database Model for Individual projectsStudentProject First NameLast NameM/FEmail addressDate of BirthNumberDate AssignedDate Due (mm/dd/yy)Grade (0 – 100)1ManyThe line between shows the relationship between entries on each table. In this case, it indicates that each student has many given many projects.
- 5. Database Model for IndividualProjectsProject Project StudentNumberDate AssignedDate Due (mm/dd/yy)Grade (0 – 100)NumberDate AssignedDate DueGradeFirst NameLast NameM/FEmail addressDate of BirthStudentFirst NameLast NameM/FEmail addressDate of Birth This model shows that each project entry is associated with a single student entry
- 6. This model shows that each Student has many project entriesHow Tables Can Be UsedThe tables can be used to get useful information about students and projectsFor example, a teacher may use the project table to count the number of projects he has to grade by counting all the projects that don’t yet have a graded recordedA teacher could also use entries in the student and project table (and the connection between them) to determine the average grade for female students versus male students Age could also be used in the analysis since date of birth is captured on the student table
- 7. Group projectsGroup projects are given to 2 or more studentsFor each group project, there is one grade given to the group. Each student in the group gets the same grade for the project.Like individual projects, the information for each group project is stored as an entry in the project table
- 8. Database Model for Group ProjectsStudentProject First NameLast NameM/FEmail addressDate of BirthNumberDate AssignedDate DueGradeManyMany The model for group projects and individual projects is the same with one exception- it shows that each project entry has many students assigned to it instead of just one.
- 9. Database Model for Group ProjectsNumberDate AssignedDate DueGradeProjectFirst NameLast NameM/FEmail addressDate of BirthStudent This model shows that a group project is assigned to many studentsDatabase Model for Group projectsStudentProject Student-Project StudentIDFirst NameLast NameM/FEmail addressDate of BirthProjectIDNumberDate AssignedDate DueGradeStudentIDProjectIDThe student-Project table associates a student with a project and therefore allows many students to be associated with a single project
- 10. Class Information5 individual projects have been assigned2 Group ProjectsThe highest possible score for a student is therefore (7*100) = 700 pointsThere are 20 students in the class – 10 boys and 10 girls
- 11. AnalysisAs part of a class analysis, using the database system, the teacher finds the following for her class:The average for the class for the group projects is 82 The total project points for the 10 girls in the class is 6820The total project points for the 10 girls in the class is 5970
- 12. Expanded ModelUsing similar concepts the model could be expanded to include concepts of teachers, classes, etcThe expanded model could look like the following