Yana P.

task-1/README.MD

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+📘 Task 1 — Library Database (3NF Normalization)
+This folder contains all files required to set up and run the database for Task 1, including the schema, seed data, ER diagram, and Docker Compose configuration.
+
+📌 1. ER Diagram
+The ER diagram is included in the repository: library_er_diagram.png
+It shows all tables and relationships in the normalized database.
+
+📌 2. Running PostgreSQL (Docker)
+A docker-compose.yml file is included to start PostgreSQL quickly.
+Start the database:
+
+```bash
+docker compose up -d
+```
+
+Check that the container is running:
+
+```bash
+docker ps
+```
+
+Connection details:
+- Host: localhost
+- Port: 5432
+- Database: library
+- User: postgres
+- Password: postgres
+
+📌 3. Apply the Schema
+Run the schema file to create all tables and constraints:
+
+```bash
+psql -h localhost -p 5432 -U postgres -d library -f schema.sql
+```
+
+📌 4. Insert Seed Data
+Load the initial dataset:
+
+```bash
+psql -h localhost -p 5432 -U postgres -d library -f seed.sql
+```
+
+This inserts:
+- members
+- cards
+- publishers
+- authors
+- tags
+- books
+- shelves
+- copies
+- borrows
+Sequences are synchronized using setval.
+
+📌 5. Tables Included
+- members
+- cards
+- publishers
+- authors
+- tags
+- books
+- shelves
+- copies
+- borrows
+- book_authors (N:M)
+- book_tags (N:M)
+
+📌 6. Relationship Types
+1:1 — members ↔ cards
+1:N — publishers → books
+1:N — books → copies
+1:N — members → borrows
+N:M — books ↔ authors
+N:M — books ↔ tags
+
+📌 7. Constraints
+PRIMARY KEY on every table
+FOREIGN KEY relationships
+UNIQUE constraints (email, ISBN, barcode, tag name, etc.)
+CHECK constraints (fine ≥ 0, valid dates, etc.)
+
+📌 8. Notes
+The schema and seed data are ready to be used in Task 2 (Java JDBC).
+The ER diagram reflects the final normalized structure.
+The database can be recreated at any time using the steps above.

task-1/docker-compose.yml

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+version: '3.9'
+
+services:
+  postgres:
+    image: postgres:16
+    container_name: library-db
+    restart: unless-stopped
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+      POSTGRES_DB: library
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+
+volumes:
+  postgres_data:

task-1/schema.sql

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--- Write here your DDL statements to create the tables for the database.
+-- Write here your DDL statements to create the tables for the database.
+
+
+
+
+-
+CREATE TABLE cards
+(
+    card_id SERIAL PRIMARY KEY,
+    card_number TEXT UNIQUE NOT NULL,
+    card_issued_on DATE NOT NULL,
+    card_expires_on DATE NOT NULL,
+    CHECK (card_expires_on > card_issued_on)
+);
+
+
+CREATE TABLE members
+(
+    member_id      SERIAL PRIMARY KEY,
+    card_id        INTEGER UNIQUE,
+    member_email   TEXT UNIQUE NOT NULL,
+    member_name    TEXT        NOT NULL,
+    member_phone   TEXT     NOT NULL,
+    member_address TEXT        NOT NULL,
+    CONSTRAINT fk_card_id
+        FOREIGN KEY (card_id)
+            REFERENCES cards (card_id) ON DELETE CASCADE
+);
+
+
+CREATE TABLE publishers
+(
+    publisher_id SERIAL PRIMARY KEY,
+    publisher_name TEXT UNIQUE NOT NULL
+);
+
+
+CREATE TABLE authors
+(
+    author_id SERIAL PRIMARY KEY,
+    author_name TEXT NOT NULL
+);
+
+
+CREATE TABLE tags
+(
+    tag_id SERIAL PRIMARY KEY,
+    tag_name VARCHAR(25) UNIQUE NOT NULL
+);
+
+
+CREATE TABLE books
+(
+    book_id SERIAL PRIMARY KEY,
+    book_isbn VARCHAR(13) UNIQUE NOT NULL,
+    book_title TEXT NOT NULL,
+    publisher_id INTEGER NOT NULL,
+    CONSTRAINT fk_publisher_id
+        FOREIGN KEY(publisher_id)
+             REFERENCES publishers (publisher_id)
+);
+
+
+CREATE TABLE book_authors
+(
+    book_id INTEGER NOT NULL,
+    author_id INTEGER NOT NULL,
+    PRIMARY KEY (book_id, author_id),
+    FOREIGN KEY(book_id) REFERENCES books (book_id) ON DELETE CASCADE,
+    FOREIGN KEY(author_id) REFERENCES authors(author_id) ON DELETE CASCADE
+
+);
+
+CREATE TABLE book_tags
+(
+    book_id INTEGER NOT NULL,
+    tag_id INTEGER NOT NULL,
+    PRIMARY KEY (book_id, tag_id),
+    FOREIGN KEY(book_id) REFERENCES books(book_id) ON DELETE CASCADE,
+    FOREIGN KEY(tag_id) REFERENCES tags(tag_id) ON DELETE CASCADE
+);
+
+
+CREATE TABLE shelves
+(
+    shelf_id SERIAL PRIMARY KEY,
+    shelf_code TEXT UNIQUE NOT NULL
+);
+
+
+CREATE TABLE copies
+(
+    copy_id SERIAL PRIMARY KEY,
+    copy_barcode TEXT UNIQUE NOT NULL,
+    book_id INTEGER NOT NULL,
+    shelf_id INTEGER,
+    CONSTRAINT fk_book_id
+        FOREIGN KEY (book_id)
+            REFERENCES books(book_id) ON DELETE CASCADE,
+    CONSTRAINT fk_shelf_id
+        FOREIGN KEY (shelf_id)
+            REFERENCES shelves(shelf_id)
+);
+
+CREATE TABLE borrows
+(
+    borrow_id SERIAL PRIMARY KEY,
+    member_id INTEGER NOT NULL,
+    copy_id INTEGER NOT NULL,
+    borrowed_at TIMESTAMP NOT NULL,
+    due_date TIMESTAMP NOT NULL,
+    returned_at TIMESTAMP,
+    fine_eur NUMERIC(8,2) NOT NULL DEFAULT 0.00,
+
+    CHECK (due_date >= borrowed_at ),
+    CHECK (returned_at IS NULL OR returned_at >= borrowed_at),
+    CHECK (fine_eur >= 0.00),
+    CONSTRAINT fk_member_id
+        FOREIGN KEY (member_id)
+            REFERENCES members(member_id),
+    CONSTRAINT fk_copy_id
+        FOREIGN KEY (copy_id)
+            REFERENCES copies(copy_id)
+);
+