Add the completed Computer Store Database project to the SQL with Pyt…

…hon track.

JetBrainsAcademy/SQL with Python Track/Easy/Computer Store Database/Computer_Store.sql

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+-- Create the Product table
+CREATE TABLE Product (
+    maker VARCHAR(50) NOT NULL,
+    model INT NOT NULL,
+    type VARCHAR(50) NOT NULL,
+    PRIMARY KEY (model)
+);
+
+-- Create the PC table
+CREATE TABLE PC (
+    code INT NOT NULL,
+    model INT NOT NULL,
+    speed INT NOT NULL,
+    ram INT NOT NULL,
+    hd INT NOT NULL,
+    cd VARCHAR(50) NOT NULL,
+    price DECIMAL(10, 2) NOT NULL,
+    PRIMARY KEY (code),
+    FOREIGN KEY (model) REFERENCES Product(model)
+);
+
+-- Create the Laptop table
+CREATE TABLE Laptop (
+    code INT NOT NULL,
+    model INT NOT NULL,
+    speed INT NOT NULL,
+    ram INT NOT NULL,
+    hd INT NOT NULL,
+    screen INT NOT NULL,
+    price DECIMAL(10, 2) NOT NULL,
+    PRIMARY KEY (code),
+    FOREIGN KEY (model) REFERENCES Product(model)
+);
+
+-- Create the Printer table
+CREATE TABLE Printer (
+    code INT NOT NULL,
+    model INT NOT NULL,
+    color CHAR(1) NOT NULL,
+    type VARCHAR(50) NOT NULL,
+    price DECIMAL(10, 2) NOT NULL,
+    PRIMARY KEY (code),
+    FOREIGN KEY (model) REFERENCES Product(model)
+);

JetBrainsAcademy/SQL with Python Track/Easy/Computer Store Database/computer_store_full_solution.sql

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+-- stage 1 completed
+SELECT model,
+    type,
+    price
+    FROM Printer
+        WHERE price > 200;
+
+-- stage 2 completed
+SELECT p.maker, p.model, l.hd, l.speed, l.price
+    FROM Product AS p
+    INNER JOIN Laptop AS l
+        ON p.model = l.model
+        WHERE l.hd >= 1000
+        ORDER BY l.hd ASC, l.speed DESC, l.price ASC;
+
+-- stage 3 completed
+SELECT COUNT(p1.maker) as number_of_unique_makers
+    FROM Product AS p1
+    WHERE (SELECT COUNT(p2.model) FROM Product AS p2
+		WHERE p2.maker = p1.maker) = 1;
+
+-- stage 4 completed
+WITH all_prices AS (
+    SELECT a.maker, a.model, b.speed, b.price
+        FROM Product a INNER JOIN PC b
+        ON a.model = b.model
+
+    UNION
+
+    SELECT a.maker, a.model, b.speed, b.price
+        FROM Product a INNER JOIN Laptop b
+        ON a.model = b.model
+),
+lowest_prices AS (
+    SELECT r.maker AS maker, r.model AS model, r.speed AS speed, r.price AS price
+        FROM all_prices r HAVING speed = ( SELECT MIN(speed) FROM all_prices )
+)
+SELECT * FROM lowest_prices;