How Can I Efficiently Store Multiple Courses for Students in a Database?

Storing Multiple Options in a Single Database Table

Problem: You want to design a database for result computation where students can have multiple courses attached to them, requiring a field within the database that can store an array of subjects.

Solution:

Data Normalization Principles:

Before diving into specific database design techniques, it's crucial to understand data normalization principles. By creating separate tables for different entities, such as students and courses, you prevent data redundancy and maintain referential integrity.

Database Structure:

To store multiple courses for each student, a junction table called SCJunction is used. This table correlates the student ID, course ID, and other relevant information, such as attendance and grade. A composite index on the columns (studentId, courseId, term) ensures fast data retrieval and prevents duplicate data entries.

Example Database Structure:

create table student (
    studentId int auto_increment primary key,
    fullName varchar(100) not null
);

create table dept (
    deptId int auto_increment primary key,
    deptName varchar(100) not null
);

create table course (
    courseId int auto_increment primary key,
    deptId int not null,
    courseName varchar(100) not null,
    CONSTRAINT fk_crs_dept FOREIGN KEY (deptId) REFERENCES dept(deptId)
);

create table SCJunction (
    id int auto_increment primary key,
    studentId int not null,
    courseId int not null,
    term int not null,
    attendance int not null,
    grade int not null,
    unique key(studentId,courseId,term),
    key (courseId,studentId),
    CONSTRAINT fk_sc_student FOREIGN KEY (studentId) REFERENCES student(studentId),
    CONSTRAINT fk_sc_courses FOREIGN KEY (courseId) REFERENCES course(courseId)
);

Advantages:

• Enforces referential integrity and prevents data corruption
• Uses efficient indexing for fast data retrieval
• Avoids data redundancy by storing each entity in a separate table

Note: While it may seem convenient to store multiple options in a single field as an array, it's generally not recommended for database design. This approach can lead to performance issues and data handling challenges. Junction tables provide a more structured and efficient solution for storing many-to-many relationships.

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