From 6514d8a7e2c6c1a8b5fa5cf8596bca4063990c13 Mon Sep 17 00:00:00 2001
From: Dmitriy-Klv <dmklvd@gmail.com>
Date: Sun, 26 Apr 2026 09:33:58 +0200
Subject: [PATCH] the task #4 from HW #4 was completed

---
 HWs/DmitriyK/HM4/hm4.db  | Bin 0 -> 12288 bytes
 HWs/DmitriyK/HM4/main.py | 110 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 HWs/DmitriyK/HM4/hm4.db
 create mode 100644 HWs/DmitriyK/HM4/main.py

diff --git a/HWs/DmitriyK/HM4/hm4.db b/HWs/DmitriyK/HM4/hm4.db
new file mode 100644
index 0000000000000000000000000000000000000000..e3d1d3fd864065748beb6375b5ff0ba22c577fd5
GIT binary patch
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diff --git a/HWs/DmitriyK/HM4/main.py b/HWs/DmitriyK/HM4/main.py
new file mode 100644
index 0000000..23d05cf
--- /dev/null
+++ b/HWs/DmitriyK/HM4/main.py
@@ -0,0 +1,110 @@
+import logging
+
+from sqlalchemy import (
+    DECIMAL,
+    Boolean,
+    Column,
+    Float,
+    ForeignKey,
+    Integer,
+    Numeric,
+    String,
+    Table,
+    create_engine,
+    func,
+)
+from sqlalchemy.orm import DeclarativeBase, declarative_base, relationship, sessionmaker
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger("sqlalchemy.engine")
+logger.setLevel(logging.INFO)
+
+Base = declarative_base()
+engine = create_engine("sqlite:///hm4.db")
+
+
+class Category(Base):
+    __tablename__ = "categories"
+    id = Column(Integer, primary_key=True)
+    name = Column(String(50))
+    description = Column(String(100))
+    in_stock = Column(Boolean, default=True)
+    products = relationship("Product", back_populates="category")
+
+
+class Product(Base):
+    __tablename__ = "products"
+    id = Column(Integer, primary_key=True)
+    name = Column(String(100), nullable=False)
+    price = Column(Numeric(precision=10, scale=2))
+    in_stock = Column(Boolean, default=True)
+    category_id = Column(Integer, ForeignKey("categories.id"))
+    category = relationship("Category", back_populates="products")
+
+
+Base.metadata.drop_all(engine)
+Base.metadata.create_all(engine)
+Session = sessionmaker(bind=engine)
+
+with Session() as session:
+    with session.begin():
+        electronics = Category(name="Electronics", description="Gadgets and devices.")
+        books = Category(name="Books", description="Printed and electronic books.")
+        clothing = Category(name="Clothing", description="Clothing for men and women.")
+        session.add_all([electronics, books, clothing])
+        session.commit()
+
+    products = [
+        Product(name="Smartphone", price=299.99, category=electronics),
+        Product(name="Laptop", price=499.99, category=electronics),
+        Product(name="Sci-Fi Novel", price=15.99, category=books),
+        Product(name="Jeans", price=40.50, category=clothing),
+        Product(name="T-shirt", price=20.00, category=clothing),
+    ]
+    session.add_all(products)
+    session.commit()
+
+with Session() as session:
+    all_categories = session.query(Category).all()
+
+    for category in all_categories:
+        print(f"\nCategory: {category.name}")
+        print(f"Description: {category.description}")
+        if category.products:
+            for product in category.products:
+                print(f"Product: {product.name:<25} | Price: {product.price:>8.2f}")
+        else:
+            print("  (No products found in this category)")
+
+
+with Session() as session:
+    target_product = session.query(Product).filter(Product.name == "Smartphone").first()
+    if target_product:
+        target_product.price = 349.99
+        session.commit()
+        print(f"Successfully updated price for: {target_product.name}")
+    else:
+        print("Product 'Smartphone' not found.")
+
+
+with Session() as session:
+    results = (
+        session.query(Product.category_id, func.count(Product.id))
+        .group_by(Product.category_id)
+        .all()
+    )
+    for cat_id, count in results:
+        print(f"Category ID: {cat_id} | Total Products: {count}")
+
+
+with Session() as session:
+    results = (
+        session.query(Product.category_id, func.count(Product.id))
+        .group_by(Product.category_id)
+        .having(func.count(Product.id) > 1)
+        .all()
+    )
+
+    print("\n--- Task 5: Categories with > 1 product ---")
+    for cat_id, count in results:
+        print(f"Category ID: {cat_id} | Total Products: {count}")