Majd w4 db

Week1/exercise3_1.js

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+const { Client } = require("pg");
+
+// PostgreSQL login (Docker HYF setup)
+const adminConfig = {
+  user: "hyfuser",
+  host: "localhost",
+  database: "hyfuser",
+  password: "hyfpassword",
+  port: 5432,
+};
+
+async function main() {
+  // Step 1 — Connect to PostgreSQL as hyfuser
+  const adminClient = new Client(adminConfig);
+  let meetupClient;
+
+  try {
+    console.log("Connecting to PostgreSQL...");
+    await adminClient.connect();
+
+    // Step 2 — Drop & recreate database meetup
+    console.log("Dropping database meetup (if exists)...");
+    await adminClient.query("DROP DATABASE IF EXISTS meetup;");
+
+    console.log("Creating database meetup...");
+    await adminClient.query("CREATE DATABASE meetup;");
+
+    // Step 3 — Connect to the new meetup database
+    meetupClient = new Client({
+      ...adminConfig,
+      database: "meetup",
+    });
+
+    await meetupClient.connect();
+    console.log("Connected to meetup database.");
+
+    // Step 4 — Create tables
+    console.log("Creating tables...");
+
+    await meetupClient.query(`
+      CREATE TABLE Invitee (
+        invitee_no SERIAL PRIMARY KEY,
+        invitee_name VARCHAR(50),
+        invited_by VARCHAR(50)
+      );
+    `);
+
+    await meetupClient.query(`
+      CREATE TABLE Room (
+        room_no SERIAL PRIMARY KEY,
+        room_name VARCHAR(50),
+        floor_number INT
+      );
+    `);
+
+    await meetupClient.query(`
+      CREATE TABLE Meeting (
+        meeting_no SERIAL PRIMARY KEY,
+        meeting_title VARCHAR(100),
+        starting_time TIME,
+        ending_time TIME,
+        room_no INT REFERENCES Room(room_no)
+      );
+    `);
+
+    // Step 5 — Insert 5 rows into each table
+    console.log("Inserting data...");
+
+    await meetupClient.query(`
+      INSERT INTO Invitee (invitee_name, invited_by) VALUES
+      ('Majd', 'HYF'),
+      ('karim', 'Majd'),
+      ('alaa', 'karim'),
+      ('rim', 'Majd'),
+      ('ivan', 'rim');
+    `);
+
+    await meetupClient.query(`
+      INSERT INTO Room (room_name, floor_number) VALUES
+      ('Blue Room', 1),
+      ('Green Room', 2),
+      ('Red Room', 3),
+      ('Yellow Room', 1),
+      ('VIP Room', 4);
+    `);
+
+    await meetupClient.query(`
+      INSERT INTO Meeting (meeting_title, starting_time, ending_time, room_no) VALUES
+      ('Frontend Session', '10:00', '11:00', 1),
+      ('Database Workshop', '12:00', '13:30', 2),
+      ('Backend Lecture', '14:00', '15:00', 3),
+      ('UX Review', '16:00', '17:00', 4),
+      ('Career Talk', '09:00', '10:00', 5);
+    `);
+
+    console.log("All data inserted successfully.");
+    console.log("Exercise 3.1 completed.");
+
+  } catch (error) {
+    console.error("ERROR:", error);
+  } finally {
+    if (meetupClient) {
+      await meetupClient.end();
+    }
+    await adminClient.end();
+  }
+}
+
+main();

Week1/exercise3_2.js

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+// exercise3_2.js
+const { Client } = require("pg");
+
+async function run() {
+  const client = new Client({
+    host: "localhost",
+    port: 5432,
+    user: "hyfuser",
+    password: "hyfpassword",
+    database: "world",
+  });
+
+  try {
+    await client.connect();
+    console.log("Connected to world database\n");
+
+    let result;
+
+    console.log("1. Countries with population > 8 million:");
+    result = await client.query(`
+      SELECT name 
+      FROM country 
+      WHERE population > 8000000;
+    `);
+    console.log(result.rows);
+
+    console.log("\n2. Countries containing 'land' in the name:");
+    result = await client.query(`
+      SELECT name 
+      FROM country 
+      WHERE name ILIKE '%land%';
+    `);
+    console.log(result.rows);
+
+    console.log("\n3. Cities with population between 500,000 and 1,000,000:");
+    result = await client.query(`
+      SELECT name 
+      FROM city 
+      WHERE population BETWEEN 500000 AND 1000000;
+    `);
+    console.log(result.rows);
+
+    console.log("\n4. Countries in Europe:");
+    result = await client.query(`
+      SELECT name 
+      FROM country 
+      WHERE continent = 'Europe';
+    `);
+    console.log(result.rows);
+
+    console.log("\n5. Countries ordered by surface area (DESC):");
+    result = await client.query(`
+      SELECT name, surfacearea 
+      FROM country 
+      ORDER BY surfacearea DESC;
+    `);
+    console.log(result.rows);
+
+    console.log("\n6. Cities in the Netherlands:");
+    result = await client.query(`
+      SELECT city.name
+      FROM city
+      JOIN country ON city.countrycode = country.code
+      WHERE country.name = 'Netherlands';
+    `);
+    console.log(result.rows);
+
+    console.log("\n7. Population of Rotterdam:");
+    result = await client.query(`
+      SELECT population 
+      FROM city 
+      WHERE name = 'Rotterdam';
+    `);
+    console.log(result.rows);
+
+    console.log("\n8. Top 10 countries by surface area:");
+    result = await client.query(`
+      SELECT name, surfacearea 
+      FROM country 
+      ORDER BY surfacearea DESC 
+      LIMIT 10;
+    `);
+    console.log(result.rows);
+
+    console.log("\n9. Top 10 most populated cities:");
+    result = await client.query(`
+      SELECT name, population 
+      FROM city 
+      ORDER BY population DESC 
+      LIMIT 10;
+    `);
+    console.log(result.rows);
+
+    console.log("\n10. Total world population:");
+    result = await client.query(`
+      SELECT SUM(population) AS world_population
+      FROM country;
+    `);
+    console.log(result.rows);
+
+    console.log("\nAll queries executed.");
+  } catch (err) {
+    console.error("ERROR:", err);
+  } finally {
+    await client.end();
+    console.log("Connection closed.");
+  }
+}
+
+run();

Week2/Week2assignment/db.js

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+import pg from 'pg';
+const { Pool } = pg;
+
+const pool = new Pool({
+    host: 'localhost',
+    user: 'hyfuser',
+    password: 'hyfpassword',
+    database: 'userdb',
+    port: 5432,
+});
+
+export default pool;

Week2/Week2assignment/ex1-keys.js

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+import pool from './db.js';
+
+async function run() {
+    try {
+        // Create authors table
+        await pool.query(`
+      CREATE TABLE IF NOT EXISTS authors (
+        author_id SERIAL PRIMARY KEY,
+        author_name VARCHAR,
+        university VARCHAR,
+        date_of_birth DATE,
+        h_index INTEGER,
+        gender VARCHAR
+      );
+    `);
+
+        // Add mentor column with foreign key
+        // We use ADD COLUMN IF NOT EXISTS to avoid errors on re-runs if supported,
+        // or catch the error. Since standard SQL doesn't support IF NOT EXISTS for columns easily in one line without PL/SQL,
+        // we will just try to add it and catch the error if it exists, or check first.
+        // However, the prompt says "Each file must execute its SQL when run".
+        // I'll assume a fresh run or handle it gracefully.
+        // Let's try to add it. If it fails because it exists, that's fine.
+
+        try {
+            await pool.query(`
+            ALTER TABLE authors 
+            ADD COLUMN mentor INTEGER REFERENCES authors(author_id);
+        `);
+        } catch (err) {
+            if (err.code !== '42701') { // duplicate_column
+                throw err;
+            }
+        }
+
+    } catch (err) {
+        console.error(err);
+    } finally {
+        await pool.end();
+    }
+}
+
+run();