diff --git a/Week3/assignment/3.1-normalization.md b/Week3/assignment/3.1-normalization.md
new file mode 100644
index 000000000..0363f730c
--- /dev/null
+++ b/Week3/assignment/3.1-normalization.md
@@ -0,0 +1,64 @@
+# 3.1 — SQL Normalization
+
+## 1. What violates 1NF?
+
+- `food_code = "C1, C2"` → multiple values in a single column.
+- `food_description = "Curry, Cake"` → same issue.
+- `dinner_date` → inconsistent formats (`2020-03-15`, `20-03-2020`, `Mar 25 '20`). It should always be stored as `DATE`.
+
+## 2. What entities can be extracted?
+
+- **Members** (club members)
+- **Dinners** (events)
+- **Venues** (locations)
+- **Foods** (dishes)
+
+Relationships:
+
+- Members ↔ Dinners (many-to-many, attendance)
+- Dinners ↔ Foods (many-to-many, menu)
+- Dinners → Venues (many-to-one)
+
+## 3. 3NF-compliant design
+
+```sql
+-- Members table
+CREATE TABLE members (
+  member_id      INTEGER PRIMARY KEY,
+  member_name    TEXT NOT NULL,
+  member_address TEXT
+);
+
+-- Venues table
+CREATE TABLE venues (
+  venue_code        TEXT PRIMARY KEY,
+  venue_description TEXT NOT NULL
+);
+
+-- Dinners table
+CREATE TABLE dinners (
+  dinner_id   TEXT PRIMARY KEY,   -- e.g. D00001001
+  dinner_date DATE NOT NULL,
+  venue_code  TEXT NOT NULL REFERENCES venues(venue_code)
+);
+
+-- Foods table
+CREATE TABLE foods (
+  food_code        TEXT PRIMARY KEY,   -- e.g. C1, S1, P1
+  food_description TEXT NOT NULL
+);
+
+-- Attendance table (members attending dinners, many-to-many)
+CREATE TABLE dinner_attendance (
+  dinner_id TEXT    NOT NULL REFERENCES dinners(dinner_id) ON DELETE CASCADE,
+  member_id INTEGER NOT NULL REFERENCES members(member_id) ON DELETE CASCADE,
+  PRIMARY KEY (dinner_id, member_id)
+);
+
+-- Dinner-foods table (foods served at each dinner, many-to-many)
+CREATE TABLE dinner_foods (
+  dinner_id TEXT NOT NULL REFERENCES dinners(dinner_id) ON DELETE CASCADE,
+  food_code TEXT NOT NULL REFERENCES foods(food_code) ON DELETE RESTRICT,
+  PRIMARY KEY (dinner_id, food_code)
+);
+```
diff --git a/Week3/assignment/3.2/transaction.js b/Week3/assignment/3.2/transaction.js
new file mode 100644
index 000000000..adb2e2329
--- /dev/null
+++ b/Week3/assignment/3.2/transaction.js
@@ -0,0 +1,75 @@
+import dotenv from "dotenv";
+import pg from "pg";
+dotenv.config();
+
+const { Client } = pg;
+
+const db = new Client({
+  host: process.env.PGHOST,
+  port: process.env.PGPORT,
+  user: process.env.PGUSER,
+  password: process.env.PGPASSWORD,
+  database: process.env.PGDATABASE || "research",
+});
+
+async function transfer(fromAcc, toAcc, amount) {
+  await db.query("BEGIN");
+  try {
+    // 1) Lock both accounts
+    const fromRes = await db.query(
+      "SELECT balance FROM account WHERE account_number = $1 FOR UPDATE",
+      [fromAcc]
+    );
+    const toRes = await db.query(
+      "SELECT balance FROM account WHERE account_number = $1 FOR UPDATE",
+      [toAcc]
+    );
+
+    if (fromRes.rowCount === 0 || toRes.rowCount === 0) {
+      throw new Error("Account not found");
+    }
+
+    const fromBal = Number(fromRes.rows[0].balance);
+    if (fromBal < amount) throw new Error("Insufficient funds");
+
+    // 2) Update balances
+    await db.query(
+      "UPDATE account SET balance = balance - $1 WHERE account_number = $2",
+      [amount, fromAcc]
+    );
+    await db.query(
+      "UPDATE account SET balance = balance + $1 WHERE account_number = $2",
+      [amount, toAcc]
+    );
+
+    // 3) Log changes
+    await db.query(
+      "INSERT INTO account_changes(account_number, amount, remark) VALUES ($1, $2, $3)",
+      [fromAcc, -amount, `transfer to ${toAcc}`]
+    );
+    await db.query(
+      "INSERT INTO account_changes(account_number, amount, remark) VALUES ($1, $2, $3)",
+      [toAcc, amount, `transfer from ${fromAcc}`]
+    );
+
+    await db.query("COMMIT");
+    console.log(` Transferred ${amount} from ${fromAcc} to ${toAcc}`);
+  } catch (e) {
+    await db.query("ROLLBACK");
+    throw e;
+  }
+}
+
+async function run() {
+  await db.connect();
+  try {
+    await transfer(101, 102, 1000.0);
+  } finally {
+    await db.end();
+  }
+}
+
+run().catch((e) => {
+  console.error("Mistake", e.message);
+  process.exit(1);
+});
diff --git a/Week3/assignment/3.2/transactions-create-tables.js b/Week3/assignment/3.2/transactions-create-tables.js
new file mode 100644
index 000000000..a2e2fb1fb
--- /dev/null
+++ b/Week3/assignment/3.2/transactions-create-tables.js
@@ -0,0 +1,45 @@
+import dotenv from "dotenv";
+import pg from "pg";
+dotenv.config();
+const { Client } = pg;
+
+const db = new Client({
+  host: process.env.PGHOST,
+  port: process.env.PGPORT,
+  user: process.env.PGUSER,
+  password: process.env.PGPASSWORD,
+  database: process.env.PGDATABASE || "research",
+});
+
+async function run() {
+  await db.connect();
+  try {
+    await db.query(`DROP TABLE IF EXISTS account_changes;`);
+    await db.query(`DROP TABLE IF EXISTS account;`);
+
+    await db.query(`
+      CREATE TABLE account (
+        account_number INTEGER PRIMARY KEY,
+        balance        NUMERIC(12,2) NOT NULL CHECK (balance >= 0)
+      );
+    `);
+
+    await db.query(`
+      CREATE TABLE account_changes (
+        change_number  BIGSERIAL PRIMARY KEY,
+        account_number INTEGER NOT NULL REFERENCES account(account_number) ON DELETE CASCADE,
+        amount         NUMERIC(12,2) NOT NULL,
+        changed_date   TIMESTAMPTZ   NOT NULL DEFAULT now(),
+        remark         TEXT NOT NULL
+      );
+    `);
+
+    console.log("tables created");
+  } finally {
+    await db.end();
+  }
+}
+run().catch((e) => {
+  console.error(e);
+  process.exit(1);
+});
diff --git a/Week3/assignment/3.2/transactions-insert-values.js b/Week3/assignment/3.2/transactions-insert-values.js
new file mode 100644
index 000000000..caca80714
--- /dev/null
+++ b/Week3/assignment/3.2/transactions-insert-values.js
@@ -0,0 +1,49 @@
+// Week3/assignment/transactions-insert-values.js
+// Inserts test accounts and initial seed transactions.
+
+import dotenv from "dotenv";
+import pg from "pg";
+dotenv.config();
+
+const { Client } = pg;
+
+const db = new Client({
+  host: process.env.PGHOST,
+  port: process.env.PGPORT,
+  user: process.env.PGUSER,
+  password: process.env.PGPASSWORD,
+  database: process.env.PGDATABASE || "research",
+});
+
+async function run() {
+  await db.connect();
+  try {
+    // Reset data
+    await db.query(`TRUNCATE account_changes, account RESTART IDENTITY;`);
+
+    // Insert accounts
+    await db.query(`
+      INSERT INTO account(account_number, balance) VALUES
+        (101, 5000.00),
+        (102, 2000.00),
+        (103, 150.00);
+    `);
+
+    // Insert account_changes log
+    await db.query(`
+      INSERT INTO account_changes(account_number, amount, remark) VALUES
+        (101, 5000.00, 'initial funding'),
+        (102, 2000.00, 'initial funding'),
+        (103, 150.00,  'initial funding');
+    `);
+
+    console.log("✅ Accounts and seed transactions inserted");
+  } finally {
+    await db.end();
+  }
+}
+
+run().catch((e) => {
+  console.error("Mistake", e.message);
+  process.exit(1);
+});
diff --git a/Week3/assignment/3.3-sql-injection.js b/Week3/assignment/3.3-sql-injection.js
new file mode 100644
index 000000000..e7cb17465
--- /dev/null
+++ b/Week3/assignment/3.3-sql-injection.js
@@ -0,0 +1,46 @@
+import dotenv from "dotenv";
+import pg from "pg";
+dotenv.config();
+
+const { Client } = pg;
+
+const db = new Client({
+host: process.env.PGHOST,
+port: process.env.PGPORT,
+user: process.env.PGUSER,
+password: process.env.PGPASSWORD,
+database: "world" // ← world DB with country table
+});
+
+async function vulnerableGetPopulation(name, code) {
+// ❌ Vulnerable: direct string interpolation
+const sql = `SELECT population FROM country WHERE name = '${name}' AND code = '${code}'`;
+const res = await db.query(sql);
+return res.rows;
+}
+
+async function safeGetPopulation(name, code) {
+// Safe: parameterized query
+const sql = `SELECT population FROM country WHERE name = $1 AND code = $2`;
+const res = await db.query(sql, [name, code]);
+return res.rows;
+}
+
+async function demo() {
+await db.connect();
+
+// Example of SQL injection
+const hacked = await vulnerableGetPopulation(`' OR '1'='1`, `' OR '1'='1`);
+console.log(" Injection result (all rows):", hacked.length);
+
+// Safe version
+const normal = await safeGetPopulation("Netherlands", "NLD");
+console.log(" Safe query result:", normal);
+
+await db.end();
+}
+
+demo().catch(e => {
+console.error(e);
+process.exit(1);
+});
diff --git a/Week3/assignment/mongo/index.js b/Week3/assignment/mongo/index.js
new file mode 100644
index 000000000..f57e28734
--- /dev/null
+++ b/Week3/assignment/mongo/index.js
@@ -0,0 +1,55 @@
+import dotenv from "dotenv";
+import { MongoClient } from "mongodb";
+dotenv.config();
+
+const uri = process.env.MONGODB_URI;
+const dbName = process.env.MONGODB_DB || "databaseWeek3";
+const collName = process.env.MONGODB_COLLECTION || "bob_ross_episodes";
+
+async function run() {
+  // 1) Connect
+  const client = new MongoClient(uri);
+  await client.connect();
+
+  try {
+    const db = client.db(dbName);
+    const coll = db.collection(collName);
+
+    // 2) C — Create (insertOne)
+    const demoDoc = {
+      title: "Demo Episode",
+      elements: ["mountain", "tree", "lake"],
+      season: 99,
+      episode: 1,
+    };
+    const insertRes = await coll.insertOne(demoDoc);
+    console.log("Inserted ID:", insertRes.insertedId.toString());
+
+    // 3) R — Read (find)
+    const mountains = await coll
+      .find({ elements: "mountain" })
+      .project({ title: 1, season: 1, episode: 1, _id: 0 })
+      .limit(5)
+      .toArray();
+    console.log("Sample with 'mountain':", mountains);
+
+    // 4) U — Update (updateMany)
+    const upd = await coll.updateMany(
+      { season: { $gte: 20 } },
+      { $set: { hasVintage: true } }
+    );
+    console.log("Updated docs:", upd.modifiedCount);
+
+    // 5) D — Delete (deleteOne) — remove demo
+    const del = await coll.deleteOne({ _id: insertRes.insertedId });
+    console.log("Deleted demo:", del.deletedCount);
+  } finally {
+    // 6) Close
+    await client.close();
+  }
+}
+
+run().catch((e) => {
+  console.error("Mongo error:", e.message);
+  process.exit(1);
+});
diff --git a/Week3/assignment/package-lock.json b/Week3/assignment/package-lock.json
new file mode 100644
index 000000000..6cf24df69
--- /dev/null
+++ b/Week3/assignment/package-lock.json
@@ -0,0 +1,176 @@
+{
+  "name": "assignment",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "assignment",
+      "version": "1.0.0",
+      "license": "ISC",
+      "dependencies": {
+        "dotenv": "^17.2.2",
+        "mongodb": "^6.19.0"
+      }
+    },
+    "node_modules/@mongodb-js/saslprep": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/@mongodb-js/saslprep/-/saslprep-1.3.0.tgz",
+      "integrity": "sha512-zlayKCsIjYb7/IdfqxorK5+xUMyi4vOKcFy10wKJYc63NSdKI8mNME+uJqfatkPmOSMMUiojrL58IePKBm3gvQ==",
+      "license": "MIT",
+      "dependencies": {
+        "sparse-bitfield": "^3.0.3"
+      }
+    },
+    "node_modules/@types/webidl-conversions": {
+      "version": "7.0.3",
+      "resolved": "https://registry.npmjs.org/@types/webidl-conversions/-/webidl-conversions-7.0.3.tgz",
+      "integrity": "sha512-CiJJvcRtIgzadHCYXw7dqEnMNRjhGZlYK05Mj9OyktqV8uVT8fD2BFOB7S1uwBE3Kj2Z+4UyPmFw/Ixgw/LAlA==",
+      "license": "MIT"
+    },
+    "node_modules/@types/whatwg-url": {
+      "version": "11.0.5",
+      "resolved": "https://registry.npmjs.org/@types/whatwg-url/-/whatwg-url-11.0.5.tgz",
+      "integrity": "sha512-coYR071JRaHa+xoEvvYqvnIHaVqaYrLPbsufM9BF63HkwI5Lgmy2QR8Q5K/lYDYo5AK82wOvSOS0UsLTpTG7uQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/webidl-conversions": "*"
+      }
+    },
+    "node_modules/bson": {
+      "version": "6.10.4",
+      "resolved": "https://registry.npmjs.org/bson/-/bson-6.10.4.tgz",
+      "integrity": "sha512-WIsKqkSC0ABoBJuT1LEX+2HEvNmNKKgnTAyd0fL8qzK4SH2i9NXg+t08YtdZp/V9IZ33cxe3iV4yM0qg8lMQng==",
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=16.20.1"
+      }
+    },
+    "node_modules/dotenv": {
+      "version": "17.2.2",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-17.2.2.tgz",
+      "integrity": "sha512-Sf2LSQP+bOlhKWWyhFsn0UsfdK/kCWRv1iuA2gXAwt3dyNabr6QSj00I2V10pidqz69soatm9ZwZvpQMTIOd5Q==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
+    "node_modules/memory-pager": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/memory-pager/-/memory-pager-1.5.0.tgz",
+      "integrity": "sha512-ZS4Bp4r/Zoeq6+NLJpP+0Zzm0pR8whtGPf1XExKLJBAczGMnSi3It14OiNCStjQjM6NU1okjQGSxgEZN8eBYKg==",
+      "license": "MIT"
+    },
+    "node_modules/mongodb": {
+      "version": "6.19.0",
+      "resolved": "https://registry.npmjs.org/mongodb/-/mongodb-6.19.0.tgz",
+      "integrity": "sha512-H3GtYujOJdeKIMLKBT9PwlDhGrQfplABNF1G904w6r5ZXKWyv77aB0X9B+rhmaAwjtllHzaEkvi9mkGVZxs2Bw==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@mongodb-js/saslprep": "^1.1.9",
+        "bson": "^6.10.4",
+        "mongodb-connection-string-url": "^3.0.0"
+      },
+      "engines": {
+        "node": ">=16.20.1"
+      },
+      "peerDependencies": {
+        "@aws-sdk/credential-providers": "^3.188.0",
+        "@mongodb-js/zstd": "^1.1.0 || ^2.0.0",
+        "gcp-metadata": "^5.2.0",
+        "kerberos": "^2.0.1",
+        "mongodb-client-encryption": ">=6.0.0 <7",
+        "snappy": "^7.3.2",
+        "socks": "^2.7.1"
+      },
+      "peerDependenciesMeta": {
+        "@aws-sdk/credential-providers": {
+          "optional": true
+        },
+        "@mongodb-js/zstd": {
+          "optional": true
+        },
+        "gcp-metadata": {
+          "optional": true
+        },
+        "kerberos": {
+          "optional": true
+        },
+        "mongodb-client-encryption": {
+          "optional": true
+        },
+        "snappy": {
+          "optional": true
+        },
+        "socks": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/mongodb-connection-string-url": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/mongodb-connection-string-url/-/mongodb-connection-string-url-3.0.2.tgz",
+      "integrity": "sha512-rMO7CGo/9BFwyZABcKAWL8UJwH/Kc2x0g72uhDWzG48URRax5TCIcJ7Rc3RZqffZzO/Gwff/jyKwCU9TN8gehA==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@types/whatwg-url": "^11.0.2",
+        "whatwg-url": "^14.1.0 || ^13.0.0"
+      }
+    },
+    "node_modules/punycode": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
+      "integrity": "sha512-vYt7UD1U9Wg6138shLtLOvdAu+8DsC/ilFtEVHcH+wydcSpNE20AfSOduf6MkRFahL5FY7X1oU7nKVZFtfq8Fg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
+    "node_modules/sparse-bitfield": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/sparse-bitfield/-/sparse-bitfield-3.0.3.tgz",
+      "integrity": "sha512-kvzhi7vqKTfkh0PZU+2D2PIllw2ymqJKujUcyPMd9Y75Nv4nPbGJZXNhxsgdQab2BmlDct1YnfQCguEvHr7VsQ==",
+      "license": "MIT",
+      "dependencies": {
+        "memory-pager": "^1.0.2"
+      }
+    },
+    "node_modules/tr46": {
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/tr46/-/tr46-5.1.1.tgz",
+      "integrity": "sha512-hdF5ZgjTqgAntKkklYw0R03MG2x/bSzTtkxmIRw/sTNV8YXsCJ1tfLAX23lhxhHJlEf3CRCOCGGWw3vI3GaSPw==",
+      "license": "MIT",
+      "dependencies": {
+        "punycode": "^2.3.1"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/webidl-conversions": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-7.0.0.tgz",
+      "integrity": "sha512-VwddBukDzu71offAQR975unBIGqfKZpM+8ZX6ySk8nYhVoo5CYaZyzt3YBvYtRtO+aoGlqxPg/B87NGVZ/fu6g==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      }
+    },
+    "node_modules/whatwg-url": {
+      "version": "14.2.0",
+      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-14.2.0.tgz",
+      "integrity": "sha512-De72GdQZzNTUBBChsXueQUnPKDkg/5A5zp7pFDuQAj5UFoENpiACU0wlCvzpAGnTkj++ihpKwKyYewn/XNUbKw==",
+      "license": "MIT",
+      "dependencies": {
+        "tr46": "^5.1.0",
+        "webidl-conversions": "^7.0.0"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    }
+  }
+}
diff --git a/Week3/assignment/package.json b/Week3/assignment/package.json
new file mode 100644
index 000000000..811da5567
--- /dev/null
+++ b/Week3/assignment/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "assignment",
+  "version": "1.0.0",
+  "main": "3.3-sql-injection.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "description": "",
+  "dependencies": {
+    "dotenv": "^17.2.2",
+    "mongodb": "^6.19.0"
+  }
+}
diff --git a/Week3/homework/mongodb/index.js b/Week3/homework/mongodb/index.js
index 41ee8b618..d85b993a0 100644
--- a/Week3/homework/mongodb/index.js
+++ b/Week3/homework/mongodb/index.js
@@ -1,94 +1,108 @@
 const { MongoClient, ServerApiVersion } = require("mongodb");
-
 const { seedDatabase } = require("./seedDatabase.js");
 
-async function createEpisodeExercise(client) {
-  /**
-   * We forgot to add the last episode of season 9. It has this information:
-   *
-   * episode: S09E13
-   * title: MOUNTAIN HIDE-AWAY
-   * elements: ["CIRRUS", "CLOUDS", "CONIFER", "DECIDIOUS", "GRASS", "MOUNTAIN", "MOUNTAINS", "RIVER", "SNOWY_MOUNTAIN", "TREE", "TREES"]
-   */
-
-  // Write code that will add this to the collection!
+const DB_NAME = "databaseWeek3";
+const COLL_NAME = "bob_ross_episodes";
 
+// CREATE
+async function createEpisodeExercise(client) {
+  const col = client.db(DB_NAME).collection(COLL_NAME);
+
+  const doc = {
+    episode: "S09E13",
+    title: "MOUNTAIN HIDE-AWAY",
+    elements: [
+      "CIRRUS",
+      "CLOUDS",
+      "CONIFER",
+      "DECIDIOUS",
+      "GRASS",
+      "MOUNTAIN",
+      "MOUNTAINS",
+      "RIVER",
+      "SNOWY_MOUNTAIN",
+      "TREE",
+      "TREES",
+    ],
+  };
+
+  const { insertedId } = await col.insertOne(doc);
   console.log(
-    `Created season 9 episode 13 and the document got the id ${"TODO: fill in variable here"}`
+    `Created season 9 episode 13 and the document got the id ${insertedId}`
   );
 }
 
+// READ
 async function findEpisodesExercises(client) {
-  /**
-   * Complete the following exercises.
-   * The comments indicate what to do and what the result should be!
-   */
-
-  // Find the title of episode 2 in season 2 [Should be: WINTER SUN]
-
-  console.log(
-    `The title of episode 2 in season 2 is ${"TODO: fill in variable here"}`
-  );
-
-  // Find the season and episode number of the episode called "BLACK RIVER" [Should be: S02E06]
-
-  console.log(
-    `The season and episode number of the "BLACK RIVER" episode is ${"TODO: fill in variable here"}`
-  );
+  const col = client.db(DB_NAME).collection(COLL_NAME);
 
-  // Find all of the episode titles where Bob Ross painted a CLIFF [Should be: NIGHT LIGHT, EVENING SEASCAPE, SURF'S UP, CLIFFSIDE, BY THE SEA, DEEP WILDERNESS HOME, CRIMSON TIDE, GRACEFUL WATERFALL]
+  // S02E02 -> WINTER SUN
+  const ep2s2 = await col.findOne({ episode: "S02E02" });
+  console.log(`The title of episode 2 in season 2 is ${ep2s2.title}`);
 
+  // BLACK RIVER -> S02E06
+  const blackRiver = await col.findOne({ title: "BLACK RIVER" });
   console.log(
-    `The episodes that Bob Ross painted a CLIFF are ${"TODO: fill in variable here"}`
+    `The season and episode number of the "BLACK RIVER" episode is ${blackRiver.episode}`
   );
 
-  // Find all of the episode titles where Bob Ross painted a CLIFF and a LIGHTHOUSE [Should be: NIGHT LIGHT]
-
+  // episodes with CLIFF
+  const cliffDocs = await col.find({ elements: "CLIFF" }).toArray();
+  const cliffTitles = cliffDocs.map((d) => d.title).join(", ");
+  console.log(`The episodes that Bob Ross painted a CLIFF are ${cliffTitles}`);
+
+  // episodes with CLIFF and LIGHTHOUSE
+  const cliffLighthouseDocs = await col
+    .find({ elements: { $all: ["CLIFF", "LIGHTHOUSE"] } })
+    .toArray();
+  const cliffLighthouseTitles = cliffLighthouseDocs
+    .map((d) => d.title)
+    .join(", ");
   console.log(
-    `The episodes that Bob Ross painted a CLIFF and a LIGHTHOUSE are ${"TODO: fill in variable here"}`
+    `The episodes that Bob Ross painted a CLIFF and a LIGHTHOUSE are ${cliffLighthouseTitles}`
   );
 }
 
+// UPDATE
 async function updateEpisodeExercises(client) {
-  /**
-   * There are some problems in the initial data that was filled in.
-   * Let's use update functions to update this information.
-   *
-   * Note: do NOT change the data.json file
-   */
-
-  // Episode 13 in season 30 should be called BLUE RIDGE FALLS, yet it is called BLUE RIDGE FALLERS now. Fix that
+  const col = client.db(DB_NAME).collection(COLL_NAME);
 
+  // S30E13 -> BLUE RIDGE FALLS
+  const updTitle = await col.updateOne(
+    { episode: "S30E13" },
+    { $set: { title: "BLUE RIDGE FALLS" } }
+  );
   console.log(
-    `Ran a command to update episode 13 in season 30 and it updated ${"TODO: fill in variable here"} episodes`
+    `Ran a command to update episode 13 in season 30 and it updated ${updTitle.modifiedCount} episodes`
   );
 
-  // Unfortunately we made a mistake in the arrays and the element type called 'BUSHES' should actually be 'BUSH' as sometimes only one bush was painted.
-  // Update all of the documents in the collection that have `BUSHES` in the elements array to now have `BUSH`
-  // It should update 120 episodes!
-
+  // BUSHES -> BUSH
+  const updBushes = await col.updateMany(
+    { elements: "BUSHES" },
+    { $set: { "elements.$": "BUSH" } }
+  );
   console.log(
-    `Ran a command to update all the BUSHES to BUSH and it updated ${"TODO: fill in variable here"} episodes`
+    `Ran a command to update all the BUSHES to BUSH and it updated ${updBushes.modifiedCount} episodes`
   );
 }
 
+// DELETE
 async function deleteEpisodeExercise(client) {
-  /**
-   * It seems an errand episode has gotten into our data.
-   * This is episode 14 in season 31. Please remove it and verify that it has been removed!
-   */
+  const col = client.db(DB_NAME).collection(COLL_NAME);
 
+  const del = await col.deleteOne({ episode: "S31E14" });
   console.log(
-    `Ran a command to delete episode and it deleted ${"TODO: fill in variable here"} episodes`
+    `Ran a command to delete episode and it deleted ${del.deletedCount} episodes`
   );
 }
 
 async function main() {
-  if (process.env.MONGODB_URL == null) {
+  if (!process.env.MONGODB_URL) {
     throw Error(
-      `You did not set up the environment variables correctly. Did you create a '.env' file and add a package to create it?`
+      `You did not set up the environment variables correctly. Did you create a '.env' file and add a package to load it?`
     );
   }
+
   const client = new MongoClient(process.env.MONGODB_URL, {
     useNewUrlParser: true,
     useUnifiedTopology: true,
@@ -98,40 +112,19 @@ async function main() {
   try {
     await client.connect();
 
-    // Seed our database
+    // Seed the database
     await seedDatabase(client);
 
-    // CREATE
+    // CRUD
     await createEpisodeExercise(client);
-
-    // READ
     await findEpisodesExercises(client);
-
-    // UPDATE
     await updateEpisodeExercises(client);
-
-    // DELETE
     await deleteEpisodeExercise(client);
   } catch (err) {
     console.error(err);
   } finally {
-    // Always close the connection at the end
-    client.close();
+    await client.close();
   }
 }
 
 main();
-
-/**
- * In the end the console should read something like this: 
-
-Created season 9 episode 13 and the document got the id 625e9addd11e82a59aa9ff93
-The title of episode 2 in season 2 is WINTER SUN
-The season and episode number of the "BLACK RIVER" episode is S02E06
-The episodes that Bob Ross painted a CLIFF are NIGHT LIGHT, EVENING SEASCAPE, SURF'S UP, CLIFFSIDE, BY THE SEA, DEEP WILDERNESS HOME, CRIMSON TIDE, GRACEFUL WATERFALL
-The episodes that Bob Ross painted a CLIFF and a LIGHTHOUSE are NIGHT LIGHT
-Ran a command to update episode 13 in season 30 and it updated 1 episodes
-Ran a command to update all the BUSHES to BUSH and it updated 120 episodes
-Ran a command to delete episode and it deleted 1 episodes
- 
-*/
diff --git a/Week3/homework/mongodb/package-lock.json b/Week3/homework/mongodb/package-lock.json
new file mode 100644
index 000000000..069e5ff44
--- /dev/null
+++ b/Week3/homework/mongodb/package-lock.json
@@ -0,0 +1,6 @@
+{
+  "name": "mongodb",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {}
+}