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Example for ER diagram part11

The document outlines an example of an Entity Relationship (ER) diagram for a college, detailing relationships among entities such as departments, courses, instructors, and students. It identifies various cardinalities, such as one-to-many between departments and courses, as well as many-to-many between courses and students. Key attributes for each entity are specified, facilitating the creation of a complete ER diagram.

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Introdaction to Python Dr. Mohammed Kassim Page 46 Example for ER diagram Example: design as (Figures and Tables) Entity Relationship diagram for a college? We have the following statements: 1. A college contains many departments 2. Each department can offer any number of courses 3. Many instructors can work in a department 4. An instructor can work only in one department 5. For each department there is a Head 6. Each instructor can take any number of courses 7. A course can be taken by only one instructor 8. A student can enroll for any number of courses 9. Each course can have any number of students Step 1: Identify the Entities What are the entities here? 1. Department 2. Course 3. Instructor 4. Student Stem 2: Identify the relationships 1. One department offers many courses. But one particular course can be offered by only one department. hence the cardinality between department and course is One to Many (1:M)
Introdaction to Python Dr. Mohammed Kassim Page 47 Example for ER diagram 2. One department has multiple instructors . But instructor belongs to only one department. Hence the cardinality between department and instructor is One to Many (1:M) 3. One course can be enrolled by many students and one student can enroll for many courses. Hence the cardinality between course and student is Many to Many (M:M) 4. One course is taught by only one instructor. But one instructor teaches many courses. Hence the cardinality between course and instructor is Many to One (M :1) Step 3: Identify the key attributes  "Departmen_Name" can identify a department uniquely.  Course_ID is the key attribute for "Course" Entity.  Student_ID is the key attribute for "Student" Entity.  Instructor_ID is the key attribute for "Instructor" Entity. Step 4: Identify other relevant attributes For the department entity, other attributes are location  For course entity, other attributes are course_name,duration  For instructor entity, other attributes are first_name, last_name, phone  For student entity, first_name, last_name, phone Step 5: Draw complete ER diagram By connecting all these details, we can now draw ER diagram as given below.
Introdaction to Python Dr. Mohammed Kassim Page 48 Example for ER diagram M 1 1 1 M M Department * Departmen_Name location Course * Course_ID * Departmen_Name * Instructor_ID course_name duration Instructor * Instructor_ID * Departmen_Name first_name last_name phone Student * Student_ID * Course_ID first_name last_name phone Entity Relationship (ER) model for a college M M M M M M ERD as Tables for College