Hussein_ShamsAddin_W4_Databases

Week1/databases/connectDatabase.js

@@ -0,0 +1,22 @@
+import pkg from 'pg';
+const { Client } = pkg;
+
+// Reusable function for connecting
+export async function connectDB() {
+  const client = new Client({
+    user: 'hyfuser',
+    host: 'localhost',
+    database: 'world',      
+    password: 'hyfpassword', 
+    port: 5432,
+  });
+
+  try {
+    await client.connect();
+    console.log(`Connected to database: ${client.database}`);
+    return client;  // return client so queries can be made outside
+  } catch (error) {
+    console.error('Connection error:', error);
+    throw error;
+  }
+}

Week1/databases/setupMeetup.js

@@ -0,0 +1,102 @@
+import pkg from 'pg';
+const { Client } = pkg;
+
+// Connect to default "postgres" database to create/drop meetup
+const defaultClient = new Client({
+  user: 'hyfuser',
+  host: 'localhost',
+  database: 'postgres',    // connect to default DB first
+  password: 'hyfpassword', // update this
+  port: 5432,
+});
+
+async function setupDatabase() {
+  try {
+    await defaultClient.connect();
+
+    // Drop and create the meetup database
+    await defaultClient.query(`DROP DATABASE IF EXISTS meetup;`);
+    await defaultClient.query(`CREATE DATABASE meetup;`);
+    console.log('Database "meetup" created.');
+
+    await defaultClient.end();
+
+    // Connect to the newly created meetup database
+    const client = new Client({
+      user: 'hyfuser',
+      host: 'localhost',
+      database: 'meetup',
+      password: 'hyfpassword', // update this
+      port: 5432,
+    });
+    await client.connect();
+
+    // Create tables
+    await client.query(`
+      CREATE TABLE Invitee (
+        invitee_no INT,
+        invitee_name VARCHAR(100),
+        invited_by VARCHAR(100)
+      );
+    `);
+
+    await client.query(`
+      CREATE TABLE Room (
+        room_no INT,
+        room_name VARCHAR(64),
+        floor_number INT
+      );
+    `);
+
+    await client.query(`
+      CREATE TABLE Meeting (
+        meeting_no INT,
+        meeting_title VARCHAR(64),
+        starting_time TIMESTAMP,
+        ending_time TIMESTAMP,
+        room_no INT
+      );
+    `);
+
+    console.log('Tables created.');
+
+    // Insert sample rows
+    await client.query(`
+      INSERT INTO Invitee (invitee_no, invitee_name, invited_by) VALUES
+      (1, 'Alice Johnson', 'Bob Smith'),
+      (2, 'Bob Smith', 'Carol White'),
+      (3, 'Carol White', 'David Lee'),
+      (4, 'David Lee', 'Alice Johnson'),
+      (5, 'Eve Brown', 'Bob Smith');
+    `);
+
+    await client.query(`
+      INSERT INTO Room (room_no, room_name, floor_number) VALUES
+      (101, 'Blue Room', 1),
+      (102, 'Green Room', 1),
+      (201, 'Yellow Room', 2),
+      (202, 'Red Room', 2),
+      (301, 'Conference Hall', 3);
+    `);
+
+    await client.query(`
+      INSERT INTO Meeting (meeting_no, meeting_title, starting_time, ending_time, room_no) VALUES
+      (1, 'Project Kickoff', '2025-09-01 09:00:00', '2025-09-01 10:00:00', 101),
+      (2, 'Design Review', '2025-09-02 11:00:00', '2025-09-02 12:30:00', 102),
+      (3, 'Team Standup', '2025-09-03 09:30:00', '2025-09-03 10:00:00', 201),
+      (4, 'Client Presentation', '2025-09-04 14:00:00', '2025-09-04 15:30:00', 202),
+      (5, 'Retrospective', '2025-09-05 16:00:00', '2025-09-05 17:00:00', 301);
+    `);
+
+    console.log('Data inserted.');
+
+    await client.end();
+    console.log('Setup complete.');
+
+  } catch (err) {
+    console.error('Error:', err);
+    await defaultClient.end();
+  }
+}
+
+setupDatabase();

Week1/databases/world.sql

@@ -8,9 +8,9 @@
 SET standard_conforming_strings = on;
 
 -- Connect to the world database or create it
--- DROP DATABASE IF EXISTS world; -- Uncomment if needed
--- CREATE DATABASE world;
--- \c world;
+DROP DATABASE IF EXISTS world; -- Uncomment if needed
+CREATE DATABASE world;
+\c world;
 
 BEGIN;
 

Week1/databases/worldStats.js

@@ -0,0 +1,94 @@
+import { connectDB } from './connectDatabase.js';
+
+async function DbQueries() {
+  const client = await connectDB();
+  try {
+    // 1. What are the names of countries with population greater than 8 million?
+    const result1 = await client.query(`
+      SELECT name
+      FROM country 
+      WHERE population > 8000000;
+    `);
+    console.log('Countries with population more than 8M:', result1.rows);
+
+    // 2. What are the names of countries that have "land" in their names?
+    const result2 = await client.query(`
+      SELECT name 
+      FROM country 
+      WHERE name ILIKE '%land%';
+    `);
+    console.log('Countries with "land" in their names:', result2.rows);
+
+    // 3. What are the names of the cities with population in between 500,000 and 1 million?
+    const result3 = await client.query(`
+        SELECT name
+        FROM CITY
+        WHERE population BETWEEN 500000 AND 1000000;
+        `)
+        console.log('Cities with population between 500,000 and 1 million:', result3.rows);
+
+    // 4. What's the name of all the countries on the continent 'Europe'?
+    const result4 = await client.query(`
+        SELECT name
+        FROM country
+        WHERE continent = 'Europe'
+        `)
+        console.log('Countries in Europe continent:', result4.rows)
+
+    // 5. List all the countries in the descending order of their surface areas.
+        const result5 = await client.query(`
+            SELECT name
+            FROM country
+            ORDER BY surfacearea DESC
+            `)
+        console.log('countries in the descending order of their surface areas:', result5.rows)
+
+    // 6. What are the names of all the cities in the Netherlands?
+        const result6 = await client.query(`
+            SELECT name
+            FROM city
+            WHERE countrycode = 'NLD'
+            `)
+            console.log('All cities in the Netherlands:', result6.rows)
+
+    // 7. What is the population of Rotterdam?
+        const result7 = await client.query(`
+            SELECT population
+            FROM city
+            WHERE name = 'Rotterdam'
+            `)
+            console.log('Population of Rotterdam is:', result7.rows)
+
+    // 8. What's the top 10 countries by Surface Area?
+        const result8 = await client.query(`
+            SELECT name
+            FROM country
+            ORDER BY surfacearea DESC
+            LIMIT 10
+            `)
+            console.log('Top 10 countries by Surface Area:', result8.rows)
+
+    // 9. What's the top 10 most populated cities?
+        const result9 = await client.query(`
+            SELECT name
+            FROM city
+            ORDER BY population DESC
+            LIMIT 10;
+            `)
+            console.log('Top 10 most populated cities:', result9.rows)
+
+    // 10. What is the population number of the world?
+        const result10 = await client.query(`
+            SELECT SUM(population)
+            FROM country
+            `)
+            console.log('The population number of the world is:', result10.rows)
+  } catch (err) {
+    console.error('Error running queries:', err);
+  } finally {
+    await client.end();
+    console.log('Connection closed.');
+  }
+}
+
+DbQueries();

Week2/assignment/.gitignore

@@ -0,0 +1,6 @@
+node_modules/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.DS_Store

Week2/assignment/README.md

@@ -0,0 +1,11 @@
+# Week 2 Assignment
+
+## Quick Setup
+
+1. Install dependencies:
+   ```bash
+   npm install
+
+2. Run one command: 
+   ```bash
+   node main.js

Week2/assignment/connectDatabase.js

@@ -0,0 +1,37 @@
+import pkg from 'pg';
+const { Client } = pkg;
+
+export async function setupDatabase(dropAndCreate = false) {
+  // Connect to default database
+  const defaultClient = new Client({
+    user: 'hyfuser',
+    host: 'localhost',
+    database: 'postgres',
+    password: 'hyfpassword',
+    port: 5432,
+  });
+
+  await defaultClient.connect();
+  console.log('Connected to default database.');
+
+  if (dropAndCreate) {
+    await defaultClient.query(`DROP DATABASE IF EXISTS research_db;`);
+    await defaultClient.query(`CREATE DATABASE research_db;`);
+    console.log('Database "research_db" created.');
+  }
+
+  await defaultClient.end();
+
+  // Connect to research_db
+  const client = new Client({
+    user: 'hyfuser',
+    host: 'localhost',
+    database: 'research_db',
+    password: 'hyfpassword',
+    port: 5432,
+  });
+
+  await client.connect();
+  console.log('Connected to "research_db".');
+  return client;
+}

Week2/assignment/exercise1_keys.js

@@ -0,0 +1,48 @@
+import { setupDatabase } from './connectDatabase.js';
+
+// Create authors table
+  async function createAuthorsTable() {
+  const client = await setupDatabase();
+  try {
+    await client.query(`
+      CREATE TABLE IF NOT EXISTS authors (
+        author_id SERIAL PRIMARY KEY,
+        author_name VARCHAR(100),
+        university VARCHAR(100),
+        date_of_birth DATE,
+        h_index INT,
+        gender VARCHAR(10)
+      );
+    `);
+    console.log('Table "authors" created successfully!');
+  } catch (error) {
+    console.error('Error creating table:', error);
+  } finally {
+    await client.end();
+  }
+}
+
+// Add mentor column
+  async function addMentorColumn() {
+  const client = await setupDatabase();
+  try {
+    await client.query(`
+      ALTER TABLE authors
+      ADD COLUMN mentor INT REFERENCES authors(author_id);
+    `);
+    console.log('Column "mentor" added successfully!');
+  } catch (error) {
+    console.error('Error adding mentor column:', error);
+  } finally {
+    await client.end();
+  }
+}
+
+export async function main1() {
+  // Drop & recreate database for a fresh start
+  const client1 = await setupDatabase(true);
+  await client1.end();
+  await createAuthorsTable();
+  await addMentorColumn();
+  console.log('3.1. Exercise 1: Keys completed successfully!');
+}