Convert ER diagram to Relational model and Normalization
- 1. Database System Assignment On Submitted To : Sir MD. Shohel Mojumder Lecturer, Bangladesh University Department of CSE Submitted By : MD. SADIQUR RAHMAN ID : 201531043092 Batch No : 43 Department of CSE BANGLADESH UNIVERSITY 15/1, Iqbal Road, Mohammadpur, Dhaka-1207
- 2. 1 Required Data Required data for creating a student marks database of a university: 1. For student information each student has a unique ID. 2. Each student has a name. 3. Each student takes a Program. 4. Versity offers courses for students. 5. Offering course have Course time limit, Section number & Room number. 6. Each Course should have a unique ID. 7. Offering Course have Semester & Year. 8. Versity takes Exam & Every exam have a specific Exam ID. 9. Each exam has subject, exam place & exam time. 10. Finally have marks of each student for each course.
- 3. 2 ER Diagram
- 4. 3 Snapshot : Student (Sid, Sname, Program, Sec_no) Course_offreing (Sec_no, Time, Room, Course_no, Semester, Year) Exam (Eid, Ename, Eplace, Etime) Takes (Sid, Eid, makes, Sec_no) Student Sid Sname Program Sec_no Course Offering Sec_no Time Room Course_no Semester Year Exam Eid Ename Eplace Etime Takes Sid Eid Sec_no Marks
- 5. 4 Tables Table made from ER diagram. Students Student ID. Name Program 10131 Akash CSE 10132 Karim BBA 10133 Jamail LAW 10134 Habib EEE Exam Exam ID. Name Place Time 43138 DBMS Mirpur 10.00 am 43139 Accounting Bobani 2.00 pm 43140 English Gulshan 12.00 pm 43141 DLD Mohakhali 10.00 am
- 6. 5 Course Offerings Time Section No Room Course No Semester Year 4 months 3A 001 CSE-312 Fall 2017 4 months 3E 122 BUS-315 Fall 2016 4 months 4C 243 ENG-112 Spring 2015 4 months 5A 359 EEE-111 Summer 2016 Course taken by Students and their marks in exams: Student ID Course No Exam ID Marks 10131 CSE-312 43138 81 10132 BUS-315 43139 68 10133 ENG-112 43140 85 10134 EEE-111 43141 81 10134 CSE-312 43138 75 10131 BUS-315 43138 68 10132 ENG-112 43140 75
- 7. 6 Normalization We will use three types of normalization: 1. First normal form(1NF) 2. Second normal form(2NF) 3. Third normal form(3NF) Let’s begin. We can normalize the marks in exams table as it’s already in first normal form. Student ID Course No Exam ID Marks 10131 CSE-312 43138 81 10132 BUS-315 43139 68 10133 ENG-112 43140 85 10134 EEE-111 43141 81 10134 CSE-312 43138 75 10131 BUS-315 43138 68 10132 ENG-112 43140 75 Now it’s time for second normal form. The roles for second normal form is: Table is in 1NF (First normal form) No non-prime attribute is dependent on the proper subset of any candidate key of table.
- 8. 7 As we can see there are two candidate keys: (Students ID, Course NO). And a non-prime attribute: (Marks). Because to find out a student exam mark in a specific subject we need that subject’s course ID/ course no. So marks a non-primitive attribute is functionally dependent on students ID and course no. both. We have to remove this dependency. We will create a table with students ID and Course No. Student ID Course No 10131 CSE-312 10132 BUS-315 10133 ENG-112 10134 EEE-111 10134 CSE-312 10131 BUS-315 10132 ENG-112
- 9. 8 And a table with Course No, Exam ID, Marks. Course No Exam ID Marks CSE-312 43138 81 BUS-315 43139 68 ENG-112 43140 85 EEE-111 43141 81 CSE-312 43138 75 BUS-315 43138 68 ENG-112 43140 75 THE END