Karim w2 db

Week1/assignment/exer1.js

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+const { Client } = require("pg");
+
+const DB_USER = "hyfuser";
+const DB_PASSWORD = "hyfpassword";
+const DB_HOST = "localhost";
+const DB_PORT = 5432;
+
+const baseConfig = {
+    host: DB_HOST,
+    port: DB_PORT,
+    user: DB_USER,
+    password: DB_PASSWORD,
+};
+
+async function withClient(database, handler) {
+    const client = new Client({ ...baseConfig, database });
+    await client.connect();
+
+    try {
+        return await handler(client);
+    } finally {
+        await client.end();
+    }
+}
+
+async function setupMeetup() {
+    try {
+        // 1) Drop & recreate database meetup
+        await withClient("postgres", async (client) => {
+            console.log("Recreating database meetup...");
+
+            await client.query("DROP DATABASE IF EXISTS meetup;");
+            await client.query("CREATE DATABASE meetup;");
+        });
+
+
+        await withClient("meetup", async (db) => {
+            console.log("Creating tables...");
+
+            await db.query(`
+        CREATE TABLE Invitee (
+          invitee_no   SERIAL PRIMARY KEY,
+          invitee_name VARCHAR(80) NOT NULL,
+          invited_by   VARCHAR(80) NOT NULL
+        );
+      `);
+
+            await db.query(`
+        CREATE TABLE Room (
+          room_no      SERIAL PRIMARY KEY,
+          room_name    VARCHAR(80) NOT NULL,
+          floor_number INTEGER     NOT NULL
+        );
+      `);
+
+            await db.query(`
+        CREATE TABLE Meeting (
+          meeting_no    SERIAL PRIMARY KEY,
+          meeting_title VARCHAR(120) NOT NULL,
+          starting_time TIMESTAMP    NOT NULL,
+          ending_time   TIMESTAMP    NOT NULL,
+          room_no       INTEGER      REFERENCES Room(room_no)
+        );
+      `);
+
+            console.log("Inserting sample data into Invitee...");
+            await db.query(`
+        INSERT INTO Invitee (invitee_name, invited_by) VALUES
+          ('Karim',  'Majd'),
+          ('Rim',    'Karim'),
+          ('Alaa',   'Karim'),
+          ('Ivan',   'Majd'),
+          ('Dima',   'Ivan');
+      `);
+
+            console.log("Inserting sample data into Room...");
+            await db.query(`
+        INSERT INTO Room (room_name, floor_number) VALUES
+          ('Alfa Room',   1),
+          ('Atlas Room',  1),
+          ('Nova Room', 2),
+          ('Fox Room', 2),
+          ('Sky Room',    3);
+      `);
+
+            console.log("Inserting sample data into Meeting...");
+            await db.query(`
+        INSERT INTO Meeting (meeting_title, starting_time, ending_time, room_no) VALUES
+          ('Intro to Databases',   '2025-11-20 09:00', '2025-11-20 10:00', 1),
+          ('SQL Practice',         '2025-11-20 10:30', '2025-11-20 11:30', 2),
+          ('Node & Postgres',      '2025-11-21 09:00', '2025-11-21 10:30', 3),
+          ('Security Session',     '2025-11-21 11:00', '2025-11-21 12:00', 4),
+          ('Retrospective Meetup', '2025-11-22 15:00', '2025-11-22 16:00', 5);
+      `);
+        });
+
+        console.log("Meetup database created and filled with data.");
+    } catch (err) {
+        console.error("Error while setting up meetup database:", err.message);
+    }
+}
+
+setupMeetup().catch((err) => {
+    console.error("Unexpected error:", err);
+});
+

Week1/assignment/exer2.js

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+const { Client } = require("pg");
+
+const DB_USER = "hyfuser";
+const DB_PASSWORD = "hyfpassword";
+const DB_HOST = "localhost";
+const DB_PORT = 5432;
+
+const client = new Client({
+    user: DB_USER,
+    password: DB_PASSWORD,
+    host: DB_HOST,
+    port: DB_PORT,
+    database: "world",
+});
+
+async function runQuery(label, sql) {
+    console.log(`\n=== ${label} ===`);
+
+    const result = await client.query(sql);
+    console.table(result.rows);
+}
+
+async function runWorldQueries() {
+
+    try {
+
+        await client.connect();
+        console.log("Connected to world database");
+
+        await runQuery("1) Countries with population greater than 8 million",
+            `
+                SELECT name, population
+                FROM country
+                WHERE population > 8000000
+                ORDER BY population DESC;
+        `);
+
+        await runQuery('2) Countries that have "land" in their names',
+            `
+                SELECT name
+                FROM country
+                WHERE name ILIKE '%land%'
+                ORDER BY name;
+        `);
+
+        await runQuery("3) Cities with population between 500,000 and 1,000,000",
+            `
+                SELECT name, population
+                FROM city
+                WHERE population BETWEEN 500000 AND 1000000
+                ORDER BY population;
+        `);
+
+        await runQuery("4) Countries on the continent 'Europe'",
+            `
+                SELECT name
+                FROM country
+                WHERE continent = 'Europe'
+                ORDER BY name;
+        `);
+
+        await runQuery("5) Countries ordered by surface area (descending)",
+            `
+                SELECT name, surfacearea
+                FROM country
+                ORDER BY surfacearea DESC;
+        `);
+
+        await runQuery("6) Cities in the Netherlands",
+            `
+                SELECT c.name
+                FROM city AS c
+                JOIN country AS co ON c.countrycode = co.code
+                WHERE co.name = 'Netherlands'
+                ORDER BY c.name;
+        `);
+
+        await runQuery("7) Population of Rotterdam",
+            `
+                SELECT population
+                FROM city
+                WHERE name = 'Rotterdam';
+        `);
+
+        await runQuery("8) Top 10 countries by surface area",
+            `
+                SELECT name, surfacearea
+                FROM country
+                ORDER BY surfacearea DESC 
+                LIMIT 10;
+        `);
+
+        await runQuery(
+            "9) Top 10 most populated cities",
+            `
+                SELECT name, population
+                FROM city
+                ORDER BY population DESC 
+                LIMIT 10;
+        `);
+
+        await runQuery(
+            "10) Total world population",
+            `
+                SELECT SUM(population) AS world_population
+                FROM country;
+        `);
+
+
+        console.log("\n All queries executed successfully.");
+
+    } catch (err) {
+
+        console.error("Error while running world queries:", err.message);
+
+    } finally {
+
+        await client.end();
+
+        console.log("Connection closed.");
+    }
+}
+
+
+runWorldQueries().catch((err) => {
+    console.error("Unexpected error:", err);
+});

Week2/assignment/db.js

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+import pg from "pg";
+
+const { Pool } = pg;
+
+const pool = new Pool({
+    host: process.env.DB_HOST ?? "localhost",
+    user: process.env.DB_USER ?? "hyfuser",
+    password: process.env.DB_PASSWORD ?? "hyfpassword",
+    database: process.env.DB_NAME ?? "research_w2",
+    port: Number(process.env.DB_PORT ?? 5432),
+});
+
+export default pool;

Week2/assignment/ex1.js

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+import pool from "./db.js";
+
+async function run() {
+    try {
+
+        await pool.query("DROP TABLE IF EXISTS authors CASCADE;");
+        await pool.query(`
+      CREATE TABLE authors (
+        author_id     SERIAL PRIMARY KEY,
+        full_name     VARCHAR(120) NOT NULL,
+        university    VARCHAR(120),
+        date_of_birth DATE,
+        h_index       INTEGER,
+        gender        VARCHAR(10)
+      );
+    `);
+
+
+        await pool.query(`
+      ALTER TABLE authors
+      ADD COLUMN mentor INTEGER;
+    `);
+
+
+        await pool.query(`
+      ALTER TABLE authors
+      ADD CONSTRAINT fk_authors_mentor
+      FOREIGN KEY (mentor)
+      REFERENCES authors (author_id)
+      ON DELETE SET NULL;
+    `);
+
+        console.log("Exercise 1: authors table + mentor FK created");
+    } catch (err) {
+        console.error("Error in ex1-keys:", err.message);
+    } finally {
+        await pool.end();
+        console.log("Connection closed");
+    }
+}
+
+run();