Building a Student Registration System with SQLite (Part 1)

Designing the Database Schema for a Student Registration System in SQLite, with Concurrency and Triggers.

Building a student registration system is a great way to learn about database design, SQL queries, and handling real-world data with SQLite. In Part 1, we’ll design the database schema and focus on the structure of the tables needed for students, courses, and enrollments.

But beyond that, we’ll implement some important features discussed in our previous blogs, such as concurrency handling, trigger automation, and indexing for performance. Let’s dive into how we can design a robust student registration system in SQLite that’s efficient, easy to manage, and handles concurrency issues well.

Step 1: Designing the Database Schema

We’ll start by creating the tables where we’ll store information about students, courses, and enrollments. Think of these tables like big filing cabinets where we store all the data in neat, organized files.

1. Students Table

This table stores important information about each student. We’ve added more fields for better real-world application, like phone_number, address, and enrollment_status. Each student gets a unique ID to make sure we can always find them.

CREATE TABLE students (
    student_id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL,
    date_of_birth TEXT,
    phone_number TEXT,
    address TEXT,
    enrollment_status TEXT DEFAULT 'Active'
);

Explanation:

• student_id: Each student gets a unique ID, like their special number, so we know who they are.

• email: This is their email address that we make sure is unique.

• phone_number and address: This is so we can contact them if we need to.

• enrollment_status: This tells us whether the student is active or graduated.

2. Courses Table

The courses table stores course details. We’ve added a course_duration, instructor, and max_enrollment to make it more comprehensive. This is like having a list of classes with their names, instructors, and how many students can join.

CREATE TABLE courses (
    course_id INTEGER PRIMARY KEY AUTOINCREMENT,
    course_name TEXT NOT NULL,
    course_code TEXT UNIQUE NOT NULL,
    course_description TEXT,
    course_duration INTEGER,
    instructor_name TEXT,
    max_enrollment INTEGER
);

Explanation:

• course_code: This is a special code for each course, like a short nickname to recognize the class easily.

• max_enrollment: This tells us how many students can join the class. We don’t want the class to be too crowded!

Example: If we want to check if there’s space for more students, we can use a trigger to make sure the class doesn’t get too full.

3. Enrollments Table

The enrollments table tracks which student is enrolled in which course. We’ve added enrollment_date, completion_date, and grade so we know when a student joined the course, when they finished, and how they did in the class.

CREATE TABLE enrollments (
    enrollment_id INTEGER PRIMARY KEY AUTOINCREMENT,
    student_id INTEGER,
    course_id INTEGER,
    enrollment_date TEXT,
    completion_date TEXT,
    grade TEXT,
    FOREIGN KEY (student_id) REFERENCES students (student_id),
    FOREIGN KEY (course_id) REFERENCES courses (course_id)
);

Explanation:

• enrollment_id: A special ID to keep track of each enrollment.

• completion_date: The date when a student finishes the course.

• grade: The grade the student receives when they finish.

Step 2: Implementing Concurrency Handling

Now, what happens if two people are trying to register for the same class at the same time? We don’t want to let them both in if the class is already full!

In SQLite, we use transactions to handle this. A transaction is like a lock on the database that says, “No one else can make changes while I’m doing this.” It helps make sure we don’t have problems like two people registering at once.

Example: Enrolling a Student in a Course

Imagine multiple users trying to enroll in the same course. To handle this, we use a transaction to check if the course is full, and only if there’s space, we will allow the student to enroll.

BEGIN TRANSACTION;

-- Check if there is room in the course
SELECT max_enrollment - (SELECT COUNT(*) FROM enrollments WHERE course_id = 1) AS available_spots
FROM courses WHERE course_id = 1;

-- If there is room, insert the enrollment record
INSERT INTO enrollments (student_id, course_id, enrollment_date) 
VALUES (1, 1, '2025-02-01');

COMMIT;

Explanation:

• BEGIN TRANSACTION: We start the transaction and lock the data, so no one else can change it until we’re done.

• available_spots: We check if there’s space in the class before enrolling the student.

• COMMIT: If everything is fine, we save the change and let the student enroll.

This makes sure that no one gets into the course if there’s no space.

Step 3: Adding Triggers for Automation

Triggers are like automatic helpers in the database. They do things for us without us having to ask every time.

Example: Automatically Update Enrollment Status

We can use a trigger to automatically update the enrollment status of a student when they graduate, for example.

CREATE TRIGGER update_enrollment_status
AFTER UPDATE ON enrollments
FOR EACH ROW
BEGIN
    -- If a student completes a course, update their status to 'Graduated'
    UPDATE students SET enrollment_status = 'Graduated' 
    WHERE student_id = NEW.student_id AND NOT EXISTS 
        (SELECT 1 FROM enrollments WHERE student_id = NEW.student_id AND grade IS NULL);
END;

Explanation:

• AFTER UPDATE: This trigger runs after an enrollment is updated, for example, when a student’s grade is added.

• NEW.student_id: We automatically check if the student has completed all courses and update their status to Graduated.

This helps automate the process so we don’t have to update each student’s status manually.

Step 4: Indexing for Better Performance

When our database gets bigger, it might take longer to find what we’re looking for. That’s when indexes come in! Think of indexes as a quick lookup guide to help us find things faster.

-- Index on student email for faster lookups
CREATE INDEX idx_student_email ON students (email);

-- Index on course code for faster course searches
CREATE INDEX idx_course_code ON courses (course_code);

-- Index on student_id for efficient enrollment queries
CREATE INDEX idx_student_id ON enrollments (student_id);

Explanation:

• Indexes help speed up searching. If we search for a student by email or a course by course_code, the database will use the index to find it faster.

Conclusion (Part 1)

In this blog, we’ve created the database schema for a Student Registration System, with tables for students, courses, and enrollments. We also incorporated key concepts from our previous blogs, such as concurrency handling using transactions, trigger automation for updating student statuses, and indexing to improve performance.

In Part 2, we’ll dive into data operations, such as enrolling students in courses, managing course capacities, and updating student grades.

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