diff --git a/Week2/assingment/3.1keys.sql b/Week2/assingment/3.1keys.sql
new file mode 100644
index 000000000..92648dcc4
--- /dev/null
+++ b/Week2/assingment/3.1keys.sql
@@ -0,0 +1,15 @@
+CREATE TABLE authors (
+    author_id      INT PRIMARY KEY,
+    author_name    VARCHAR(255),
+    university     VARCHAR(255),
+    date_of_birth  DATE,
+    h_index        INT,
+    gender         VARCHAR(20)
+);
+
+ALTER TABLE authors
+ADD mentor INT;
+
+ALTER TABLE authors
+ADD CONSTRAINT fk_mentor
+FOREIGN KEY (mentor) REFERENCES authors(author_id);
\ No newline at end of file
diff --git a/Week2/assingment/3.2relationship.sql b/Week2/assingment/3.2relationship.sql
new file mode 100644
index 000000000..404681a86
--- /dev/null
+++ b/Week2/assingment/3.2relationship.sql
@@ -0,0 +1,93 @@
+CREATE TABLE authors (
+    author_id INT PRIMARY KEY,
+    author_name VARCHAR(255),
+    university VARCHAR(255),
+    date_of_birth DATE,
+    h_index INT,
+    gender VARCHAR(20),
+    mentor INT,
+    CONSTRAINT fk_author_mentor
+        FOREIGN KEY (mentor) REFERENCES authors(author_id)
+);
+
+
+CREATE TABLE research_papers (
+    paper_id INT PRIMARY KEY,
+    paper_title VARCHAR(255),
+    conference VARCHAR(255),
+    publish_date DATE
+);
+
+CREATE TABLE author_papers (
+    author_id INT,
+    paper_id INT,
+    PRIMARY KEY (author_id, paper_id),
+    FOREIGN KEY (author_id) REFERENCES authors(author_id),
+    FOREIGN KEY (paper_id) REFERENCES research_papers(paper_id)
+);
+
+INSERT INTO authors (author_id, author_name, university, date_of_birth, h_index, gender, mentor) VALUES
+(1, 'Alice Johnson', 'MIT', '1980-05-12', 40, 'F', NULL),
+(2, 'Bob Smith', 'Harvard', '1975-09-22', 55, 'M', 1),
+(3, 'Clara Lee', 'Stanford', '1988-03-10', 32, 'F', 1),
+(4, 'David Brown', 'Oxford', '1982-12-01', 29, 'M', 2),
+(5, 'Eva Green', 'Cambridge', '1990-07-16', 27, 'F', 3),
+(6, 'Frank Moore', 'ETH Zurich', '1979-11-05', 48, 'M', 2),
+(7, 'Grace Kim', 'Seoul University', '1987-04-21', 35, 'F', 3),
+(8, 'Henry Wilson', 'TU Delft', '1983-06-14', 38, 'M', 1),
+(9, 'Isabella Garcia', 'UPenn', '1992-08-13', 20, 'F', 5),
+(10,'Jack Miller', 'Carnegie Mellon', '1986-01-19', 30, 'M', 6),
+(11,'Karen Adams', 'UCLA', '1984-02-28', 42, 'F', 2),
+(12,'Leo Turner', 'Toronto University', '1991-09-30', 25, 'M', 7),
+(13,'Mia Scott', 'NYU', '1985-10-25', 39, 'F', 11),
+(14,'Noah Bennett', 'Columbia', '1989-12-12', 33, 'M', 3),
+(15,'Olivia Clark', 'Princeton', '1993-03-09', 18, 'F', 5);
+
+INSERT INTO research_papers (paper_id, paper_title, conference, publish_date) VALUES
+(1, 'Deep Learning in Robotics', 'ICRA', '2020-05-10'),
+(2, 'Quantum Computing Advances', 'QIP', '2021-01-15'),
+(3, 'Neural Networks Optimization', 'NeurIPS', '2019-12-05'),
+(4, 'AI in Healthcare', 'AAAI', '2020-02-10'),
+(5, 'Reinforcement Learning Methods', 'ICML', '2021-07-18'),
+(6, 'Graph Neural Networks', 'ICLR', '2022-04-25'),
+(7, 'Computer Vision Trends', 'CVPR', '2018-06-22'),
+(8, 'Natural Language Processing Models', 'ACL', '2022-05-13'),
+(9, 'Autonomous Systems', 'RSS', '2019-06-10'),
+(10,'Distributed Machine Learning', 'KDD', '2020-08-24'),
+(11,'Brain-Inspired Computing', 'CogSci', '2018-07-18'),
+(12,'Ethics in AI', 'AIES', '2021-03-12'),
+(13,'Robotics Path Planning', 'ICRA', '2022-05-11'),
+(14,'Federated Learning', 'NeurIPS', '2021-12-03'),
+(15,'Sparse Neural Nets', 'ICML', '2020-07-20'),
+(16,'Speech Recognition Models', 'INTERSPEECH', '2019-09-15'),
+(17,'Cryptography with AI', 'Crypto', '2022-08-07'),
+(18,'Machine Learning Security', 'USENIX', '2021-08-02'),
+(19,'Vision Transformers', 'CVPR', '2021-06-15'),
+(20,'Probabilistic Models', 'UAI', '2020-07-30'),
+(21,'Bio-informatics and ML', 'ISMB', '2022-07-12'),
+(22,'Large-Scale Datasets', 'BigData', '2019-12-20'),
+(23,'AI for Climate Science', 'AGU', '2021-12-10'),
+(24,'Neuroscience + AI', 'COSYNE', '2020-03-05'),
+(25,'Robust ML Models', 'ICML', '2022-07-25'),
+(26,'Explainable AI', 'IJCAI', '2020-07-12'),
+(27,'GANs Advances', 'ECCV', '2018-10-08'),
+(28,'Meta Learning', 'ICLR', '2019-04-10'),
+(29,'Hybrid Quantum AI', 'QIP', '2022-01-22'),
+(30,'AI-Driven Optimization', 'GECCO', '2020-07-11');
+
+INSERT INTO author_papers (author_id, paper_id) VALUES
+(1,1),(1,3),(1,10),
+(2,2),(2,14),(2,18),
+(3,3),(3,6),(3,25),
+(4,4),(4,11),
+(5,5),(5,21),
+(6,6),(6,18),(6,29),
+(7,7),(7,8),
+(8,9),(8,20),
+(9,12),(9,23),
+(10,10),(10,24),
+(11,11),(11,14),(11,26),
+(12,13),(12,28),
+(13,15),(13,19),
+(14,16),(14,27),
+(15,17),(15,30);
diff --git a/Week2/assingment/3.3joins.sql b/Week2/assingment/3.3joins.sql
new file mode 100644
index 000000000..550056bbd
--- /dev/null
+++ b/Week2/assingment/3.3joins.sql
@@ -0,0 +1,13 @@
+SELECT 
+    a.author_name AS author,
+    m.author_name AS mentor
+FROM authors a
+LEFT JOIN authors m ON a.mentor = m.author_id;
+
+SELECT 
+    a.author_name,
+    rp.paper_title
+FROM authors a
+LEFT JOIN author_papers ap ON a.author_id = ap.author_id
+LEFT JOIN research_papers rp ON ap.paper_id = rp.paper_id;
+
diff --git a/Week2/assingment/3.4aggregate_functions.sql b/Week2/assingment/3.4aggregate_functions.sql
new file mode 100644
index 000000000..024f41d97
--- /dev/null
+++ b/Week2/assingment/3.4aggregate_functions.sql
@@ -0,0 +1,35 @@
+SELECT 
+    rp.paper_title,
+    COUNT(ap.author_id) AS author_count
+FROM research_papers rp
+LEFT JOIN author_papers ap ON rp.paper_id = ap.paper_id
+GROUP BY rp.paper_id, rp.paper_title;
+
+
+SELECT COUNT(*) AS women_papers
+FROM author_papers ap
+JOIN authors a ON ap.author_id = a.author_id
+WHERE a.gender = 'F';
+
+
+SELECT 
+    university,
+    AVG(h_index) AS avg_h_index
+FROM authors
+GROUP BY university;
+
+
+SELECT
+    a.university,
+    COUNT(ap.paper_id) AS paper_count
+FROM authors a
+LEFT JOIN author_papers ap ON a.author_id = ap.author_id
+GROUP BY a.university;
+
+
+SELECT
+    university,
+    MIN(h_index) AS min_h_index,
+    MAX(h_index) AS max_h_index
+FROM authors
+GROUP BY university;
diff --git a/Week2/prep/Database ER diagram (crow's foot).png b/Week2/prep/Database ER diagram (crow's foot).png
new file mode 100644
index 000000000..579c05848
Binary files /dev/null and b/Week2/prep/Database ER diagram (crow's foot).png differ
diff --git a/Week2/prep/Lucid connection.png b/Week2/prep/Lucid connection.png
new file mode 100644
index 000000000..8321abffd
Binary files /dev/null and b/Week2/prep/Lucid connection.png differ
diff --git a/Week2/prep/w1-prep-exe.sql b/Week2/prep/w1-prep-exe.sql
new file mode 100644
index 000000000..584bf10ec
--- /dev/null
+++ b/Week2/prep/w1-prep-exe.sql
@@ -0,0 +1,111 @@
+-- Очищаем существующие таблицы (для повторного запуска) -- Drop existing tables (for re-running the script)
+DROP TABLE IF EXISTS cuisines CASCADE;
+DROP TABLE IF EXISTS main_ingredients CASCADE;
+DROP TABLE IF EXISTS ingredients CASCADE;
+DROP TABLE IF EXISTS categories CASCADE;
+DROP TABLE IF EXISTS cooking_methods CASCADE;
+DROP TABLE IF EXISTS recipes CASCADE;
+DROP TABLE IF EXISTS recipe_categories CASCADE;
+DROP TABLE IF EXISTS recipe_ingredients CASCADE;
+DROP TABLE IF EXISTS recipe_methods CASCADE;
+DROP TABLE IF EXISTS recipe_ingredient_amounts CASCADE;
+
+
+
+---------------------------------------------------------
+-- 1. Таблица кухонь (Italian, Chinese, Japanese…) -- Table of Cuisines (Italian, Chinese, Japanese…)
+---------------------------------------------------------
+CREATE TABLE cuisines (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL UNIQUE
+);
+
+---------------------------------------------------------
+-- 2. Таблица основных ингредиентов (мясо, рыба, овощи) -- Table of Main Ingredients (meat, fish, vegetables)
+---------------------------------------------------------
+CREATE TABLE main_ingredients (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(150) NOT NULL UNIQUE
+);
+
+---------------------------------------------------------
+-- 3. Таблица всех возможных ингредиентов (морковь, масло, соль) -- Table of All Possible Ingredients (carrot, oil, salt)
+---------------------------------------------------------
+CREATE TABLE ingredients (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(150) NOT NULL UNIQUE
+);
+
+---------------------------------------------------------
+-- 4. Таблица категорий (суп, салат, десерт, завтрак) -- Table of Categories (soup, salad, dessert, breakfast)
+---------------------------------------------------------
+CREATE TABLE categories (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL UNIQUE
+);
+
+---------------------------------------------------------
+-- 5. Таблица методов приготовления (жарка, запекание, варка) -- Table of Cooking Methods (frying, baking, boiling)
+---------------------------------------------------------
+CREATE TABLE cooking_methods (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL UNIQUE
+);
+
+---------------------------------------------------------
+-- 6. Главная таблица рецептов -- Main Recipes Table
+---------------------------------------------------------
+CREATE TABLE recipes (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(255) NOT NULL,
+    cuisine_id INT,
+    main_ingredient_id INT,
+    FOREIGN KEY (cuisine_id) REFERENCES cuisines(id),
+    FOREIGN KEY (main_ingredient_id) REFERENCES main_ingredients(id)
+);
+
+---------------------------------------------------------
+-- 7. Связь рецепт ↔ категории (many-to-many) -- Recipe ↔ Categories Relationship (many-to-many)
+---------------------------------------------------------
+CREATE TABLE recipe_categories (
+    recipe_id INT NOT NULL,
+    category_id INT NOT NULL,
+    PRIMARY KEY (recipe_id, category_id),
+    FOREIGN KEY (recipe_id) REFERENCES recipes(id),
+    FOREIGN KEY (category_id) REFERENCES categories(id)
+);
+
+---------------------------------------------------------
+-- 8. Связь рецепт ↔ ингредиенты (many-to-many) -- Recipe ↔ Ingredients Relationship (many-to-many)
+---------------------------------------------------------
+CREATE TABLE recipe_ingredients (
+    recipe_id INT NOT NULL,
+    ingredient_id INT NOT NULL,
+    amount VARCHAR(50),  -- например "200 г", "1 ст.л."
+    PRIMARY KEY (recipe_id, ingredient_id),
+    FOREIGN KEY (recipe_id) REFERENCES recipes(id),
+    FOREIGN KEY (ingredient_id) REFERENCES ingredients(id)
+);
+
+---------------------------------------------------------
+-- 9. Связь рецепт ↔ методы приготовления (many-to-many) -- Recipe ↔ Cooking Methods Relationship (many-to-many)
+---------------------------------------------------------
+CREATE TABLE recipe_methods (
+    recipe_id INT NOT NULL,
+    method_id INT NOT NULL,
+    PRIMARY KEY (recipe_id, method_id),
+    FOREIGN KEY (recipe_id) REFERENCES recipes(id),
+    FOREIGN KEY (method_id) REFERENCES cooking_methods(id)
+);
+
+---------------------------------------------------------
+-- 10. кол-во ингредиентов в рецепте -- Quantity of Ingredients in Recipe
+---------------------------------------------------------
+CREATE TABLE recipe_ingredient_amounts (
+    recipe_id INT NOT NULL,
+    ingredient_id INT NOT NULL,
+    amount VARCHAR(50) NOT NULL,  -- например "200 г", "1 ст.л."
+    PRIMARY KEY (recipe_id, ingredient_id),
+    FOREIGN KEY (recipe_id) REFERENCES recipes(id),
+    FOREIGN KEY (ingredient_id) REFERENCES ingredients(id)
+);  
\ No newline at end of file
diff --git a/Week2/prep/w2-prep-insert-mok-data.sql b/Week2/prep/w2-prep-insert-mok-data.sql
new file mode 100644
index 000000000..05a9b7d77
--- /dev/null
+++ b/Week2/prep/w2-prep-insert-mok-data.sql
@@ -0,0 +1,98 @@
+-- ==========================================
+-- Mock data inserts for Week 2 Prep Exercise
+-- ==========================================
+
+-- 1. Cuisines
+INSERT INTO cuisines (name) VALUES
+('Japanese')
+ON CONFLICT (name) DO NOTHING;
+
+-- 2. Main ingredients
+INSERT INTO main_ingredients (name) VALUES
+('Cheese'),
+('Vegetables'),
+('Pasta'),
+('Eggs')
+ON CONFLICT (name) DO NOTHING;
+
+-- 3. Categories
+INSERT INTO categories (name) VALUES
+('Cake'),
+('No-Bake'),
+('Vegetarian'),
+('Vegan'),
+('Gluten-Free'),
+('Japanese')
+ON CONFLICT (name) DO NOTHING;
+
+-- 4. Ingredients
+INSERT INTO ingredients (name) VALUES
+('Cheese'),
+('Vegetables'),
+('Pasta'),
+('Eggs'),
+('Condensed milk'),
+('Cream Cheese'),
+('Lemon Juice'),
+('Pie Crust'),
+('Cherry Jam'),
+('Brussels Sprouts'),
+('Sesame seeds'),
+('Pepper'),
+('Salt'),
+('Olive oil'),
+('Macaroni'),
+('Butter'),
+('Flour'),
+('Milk'),
+('Shredded Cheddar cheese'),
+('Soy sauce'),
+('Sugar')
+ON CONFLICT (name) DO NOTHING;
+
+-- 5. Recipes
+INSERT INTO recipes (name, cuisine_id, main_ingredient_id) VALUES
+('No-Bake Cheesecake', NULL, 1),
+('Roasted Brussels Sprouts', NULL, 2),
+('Mac & Cheese', NULL, 3),
+('Tamagoyaki Japanese Omelette', 1, 4)
+ON CONFLICT DO NOTHING;
+
+-- 6. Recipe ↔ Categories
+INSERT INTO recipe_categories (recipe_id, category_id) VALUES
+(1, 1), (1, 2), (1, 3),
+(2, 4), (2, 5),
+(3, 3),
+(4, 3), (4, 6)
+ON CONFLICT DO NOTHING;
+
+-- 7. Recipe ↔ Ingredients
+INSERT INTO recipe_ingredients (recipe_id, ingredient_id, amount) VALUES
+-- No-Bake Cheesecake
+(1, 5, '200 ml'),
+(1, 6, '250 g'),
+(1, 7, '1 tbsp'),
+(1, 8, '1 crust'),
+(1, 9, '2 tbsp'),
+-- Roasted Brussels Sprouts
+(2, 10, '500 g'),
+(2, 7, '1 tbsp'),
+(2, 11, '1 tsp'),
+(2, 12, '1 tsp'),
+(2, 13, '1 tsp'),
+(2, 14, '2 tbsp'),
+-- Mac & Cheese
+(3, 15, '200 g'),
+(3, 16, '50 g'),
+(3, 17, '2 tbsp'),
+(3, 13, '1 tsp'),
+(3, 12, '1 tsp'),
+(3, 18, '200 ml'),
+(3, 19, '150 g'),
+-- Tamagoyaki Japanese Omelette
+(4, 4, '4'),
+(4, 20, '1 tbsp'),
+(4, 21, '1 tsp'),
+(4, 13, '1 tsp'),
+(4, 14, '1 tbsp')
+ON CONFLICT DO NOTHING;
\ No newline at end of file
diff --git a/Week2/prep/w2-request.sql b/Week2/prep/w2-request.sql
new file mode 100644
index 000000000..6e076e107
--- /dev/null
+++ b/Week2/prep/w2-request.sql
@@ -0,0 +1,24 @@
+-- 1. All vegetarian recipes with potatoes (но картошки нет в данных)
+SELECT r.name AS recipe_name
+FROM recipes r
+JOIN recipe_categories rc ON r.id = rc.recipe_id  
+JOIN categories c ON rc.category_id = c.id
+WHERE c.name = 'Vegetarian';
+
+-- 2. All cakes that do not need baking
+SELECT r.name AS recipe_name
+FROM recipes r
+JOIN recipe_categories rc1 ON r.id = rc1.recipe_id
+JOIN categories c1 ON rc1.category_id = c1.id
+JOIN recipe_categories rc2 ON r.id = rc2.recipe_id  
+JOIN categories c2 ON rc2.category_id = c2.id
+WHERE c1.name = 'Cake' AND c2.name = 'No-Bake';
+
+-- 3. All vegan and Japanese recipes
+SELECT r.name AS recipe_name
+FROM recipes r
+JOIN recipe_categories rc1 ON r.id = rc1.recipe_id
+JOIN categories c1 ON rc1.category_id = c1.id
+JOIN recipe_categories rc2 ON r.id = rc2.recipe_id
+JOIN categories c2 ON rc2.category_id = c2.id
+WHERE c1.name = 'Vegan' AND c2.name = 'Japanese';
\ No newline at end of file